215 lines
6.8 KiB
Diff
215 lines
6.8 KiB
Diff
From baae5b4a06c905d9f52ed1f922a0d7d0625d11cf Mon Sep 17 00:00:00 2001
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From: Martin Kletzander <nert.pinx@gmail.com>
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Date: Wed, 1 Feb 2023 15:36:41 +0100
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Subject: [PATCH] find_new_[gu]id(): Skip over IDs that are reserved for legacy
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reasons
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Some programs don't support `(uint16_t) -1` or `(uint32_t) -1` as user
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or group IDs. This is because `-1` is used as an error code or as an
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unspecified ID, e.g. in `chown(2)` parameters, and in the past, `gid_t`
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and `uid_t` have changed width. For legacy reasons, those values have
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been kept reserved in programs today (for example systemd does this; see
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the documentation in the link below).
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This should not be confused with catching overflow in the ID values,
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since that is already caught by our ERANGE checks. This is about not
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using reserved values that have been reserved for legacy reasons.
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Link: <https://systemd.io/UIDS-GIDS/>
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Reviewed-by: Alejandro Colomar <alx@kernel.org>
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Signed-off-by: Martin Kletzander <mkletzan@redhat.com>
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---
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libmisc/find_new_gid.c | 38 ++++++++++++++++++++++++++++----------
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libmisc/find_new_uid.c | 38 ++++++++++++++++++++++++++++----------
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2 files changed, 56 insertions(+), 20 deletions(-)
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diff --git a/libmisc/find_new_gid.c b/libmisc/find_new_gid.c
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index 70ba95a2..da1d8d55 100644
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--- a/libmisc/find_new_gid.c
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+++ b/libmisc/find_new_gid.c
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@@ -98,6 +98,7 @@ static int get_ranges (bool sys_group, gid_t *min_id, gid_t *max_id,
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*
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* On success, return 0
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* If the ID is in use, return EEXIST
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+ * If the ID might clash with -1, return EINVAL
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* If the ID is outside the range, return ERANGE
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* In other cases, return errno from getgrgid()
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*/
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@@ -111,6 +112,11 @@ static int check_gid (const gid_t gid,
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return ERANGE;
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}
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+ /* Check for compatibility with 16b and 32b gid_t error codes */
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+ if (gid == UINT16_MAX || gid == UINT32_MAX) {
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+ return EINVAL;
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+ }
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+
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/*
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* Check whether we already detected this GID
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* using the gr_next() loop
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@@ -182,10 +188,10 @@ int find_new_gid (bool sys_group,
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* gr_locate_gid() found the GID in an as-yet uncommitted
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* entry. We'll proceed below and auto-set a GID.
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*/
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- } else if (result == EEXIST || result == ERANGE) {
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+ } else if (result == EEXIST || result == ERANGE || result == EINVAL) {
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/*
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* Continue on below. At this time, we won't
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- * treat these two cases differently.
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+ * treat these three cases differently.
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*/
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} else {
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/*
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@@ -296,8 +302,11 @@ int find_new_gid (bool sys_group,
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*gid = id;
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free (used_gids);
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return 0;
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- } else if (result == EEXIST) {
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- /* This GID is in use, we'll continue to the next */
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+ } else if (result == EEXIST || result == EINVAL) {
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+ /*
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+ * This GID is in use or unusable, we'll
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+ * continue to the next.
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+ */
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} else {
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/*
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* An unexpected error occurred.
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@@ -339,8 +348,11 @@ int find_new_gid (bool sys_group,
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*gid = id;
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free (used_gids);
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return 0;
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- } else if (result == EEXIST) {
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- /* This GID is in use, we'll continue to the next */
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+ } else if (result == EEXIST || result == EINVAL) {
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+ /*
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+ * This GID is in use or unusable, we'll
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+ * continue to the next.
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+ */
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} else {
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/*
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* An unexpected error occurred.
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@@ -399,8 +411,11 @@ int find_new_gid (bool sys_group,
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*gid = id;
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free (used_gids);
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return 0;
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- } else if (result == EEXIST) {
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- /* This GID is in use, we'll continue to the next */
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+ } else if (result == EEXIST || result == EINVAL) {
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+ /*
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+ * This GID is in use or unusable, we'll
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+ * continue to the next.
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+ */
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} else {
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/*
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* An unexpected error occurred.
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@@ -442,8 +457,11 @@ int find_new_gid (bool sys_group,
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*gid = id;
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free (used_gids);
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return 0;
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- } else if (result == EEXIST) {
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- /* This GID is in use, we'll continue to the next */
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+ } else if (result == EEXIST || result == EINVAL) {
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+ /*
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+ * This GID is in use or unusable, we'll
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+ * continue to the next.
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+ */
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} else {
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/*
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* An unexpected error occurred.
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diff --git a/libmisc/find_new_uid.c b/libmisc/find_new_uid.c
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index 6b71dfe5..09885236 100644
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--- a/libmisc/find_new_uid.c
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+++ b/libmisc/find_new_uid.c
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@@ -98,6 +98,7 @@ static int get_ranges (bool sys_user, uid_t *min_id, uid_t *max_id,
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*
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* On success, return 0
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* If the ID is in use, return EEXIST
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+ * If the ID might clash with -1, return EINVAL
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* If the ID is outside the range, return ERANGE
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* In other cases, return errno from getpwuid()
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*/
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@@ -111,6 +112,11 @@ static int check_uid(const uid_t uid,
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return ERANGE;
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}
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+ /* Check for compatibility with 16b and 32b uid_t error codes */
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+ if (uid == UINT16_MAX || uid == UINT32_MAX) {
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+ return EINVAL;
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+ }
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+
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/*
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* Check whether we already detected this UID
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* using the pw_next() loop
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@@ -182,10 +188,10 @@ int find_new_uid(bool sys_user,
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* pw_locate_uid() found the UID in an as-yet uncommitted
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* entry. We'll proceed below and auto-set an UID.
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*/
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- } else if (result == EEXIST || result == ERANGE) {
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+ } else if (result == EEXIST || result == ERANGE || result == EINVAL) {
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/*
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* Continue on below. At this time, we won't
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- * treat these two cases differently.
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+ * treat these three cases differently.
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*/
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} else {
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/*
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@@ -296,8 +302,11 @@ int find_new_uid(bool sys_user,
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*uid = id;
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free (used_uids);
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return 0;
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- } else if (result == EEXIST) {
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- /* This UID is in use, we'll continue to the next */
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+ } else if (result == EEXIST || result == EINVAL) {
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+ /*
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+ * This GID is in use or unusable, we'll
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+ * continue to the next.
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+ */
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} else {
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/*
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* An unexpected error occurred.
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@@ -339,8 +348,11 @@ int find_new_uid(bool sys_user,
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*uid = id;
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free (used_uids);
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return 0;
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- } else if (result == EEXIST) {
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- /* This UID is in use, we'll continue to the next */
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+ } else if (result == EEXIST || result == EINVAL) {
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+ /*
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+ * This GID is in use or unusable, we'll
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+ * continue to the next.
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+ */
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} else {
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/*
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* An unexpected error occurred.
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@@ -399,8 +411,11 @@ int find_new_uid(bool sys_user,
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*uid = id;
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free (used_uids);
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return 0;
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- } else if (result == EEXIST) {
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- /* This UID is in use, we'll continue to the next */
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+ } else if (result == EEXIST || result == EINVAL) {
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+ /*
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+ * This GID is in use or unusable, we'll
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+ * continue to the next.
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+ */
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} else {
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/*
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* An unexpected error occurred.
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@@ -442,8 +457,11 @@ int find_new_uid(bool sys_user,
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*uid = id;
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free (used_uids);
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return 0;
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- } else if (result == EEXIST) {
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- /* This UID is in use, we'll continue to the next */
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+ } else if (result == EEXIST || result == EINVAL) {
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+ /*
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+ * This GID is in use or unusable, we'll
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+ * continue to the next.
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+ */
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} else {
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/*
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* An unexpected error occurred.
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--
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2.40.1
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