Fix invalid element address calculation (#1801109)

This commit is contained in:
Ryan O'Hara 2020-03-16 14:04:40 -05:00
parent f8bc1dd91a
commit 2d262a490f
3 changed files with 125 additions and 84 deletions

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@ -1,83 +0,0 @@
From a873c161d251abd025008034c0ddef8cd7f39511 Mon Sep 17 00:00:00 2001
From: Willy Tarreau <w@1wt.eu>
Date: Mon, 29 Oct 2018 18:02:54 +0100
Subject: BUG/MEDIUM: auth/threads: use of crypt() is not thread-safe
It was reported here that authentication may fail when threads are
enabled :
https://bugzilla.redhat.com/show_bug.cgi?id=1643941
While I couldn't reproduce the issue, it's obvious that there is a
problem with the use of the non-reentrant crypt() function there.
On Linux systems there's crypt_r() but not on the vast majority of
other ones. Thus a first approach consists in placing a lock around
this crypt() call. Another patch may relax it when crypt_r() is
available.
This fix must be backported to 1.8. Thanks to Ryan O'Hara for the
quick notification.
(cherry picked from commit 34d4b525a129baa6f52a930ae629ddb1ba4255c2)
Signed-off-by: Willy Tarreau <w@1wt.eu>
---
include/common/hathreads.h | 2 ++
src/auth.c | 7 +++++++
2 files changed, 9 insertions(+)
diff --git a/include/common/hathreads.h b/include/common/hathreads.h
index 44bd66d1d..24fb1d1a7 100644
--- a/include/common/hathreads.h
+++ b/include/common/hathreads.h
@@ -373,6 +373,7 @@ enum lock_label {
START_LOCK,
TLSKEYS_REF_LOCK,
PENDCONN_LOCK,
+ AUTH_LOCK,
LOCK_LABELS
};
struct lock_stat {
@@ -495,6 +496,7 @@ static inline const char *lock_label(enum lock_label label)
case START_LOCK: return "START";
case TLSKEYS_REF_LOCK: return "TLSKEYS_REF";
case PENDCONN_LOCK: return "PENDCONN";
+ case AUTH_LOCK: return "AUTH";
case LOCK_LABELS: break; /* keep compiler happy */
};
/* only way to come here is consecutive to an internal bug */
diff --git a/src/auth.c b/src/auth.c
index a2c689f76..e0fb13522 100644
--- a/src/auth.c
+++ b/src/auth.c
@@ -28,6 +28,7 @@
#include <types/global.h>
#include <common/config.h>
#include <common/errors.h>
+#include <common/hathreads.h>
#include <proto/acl.h>
#include <proto/log.h>
@@ -37,6 +38,10 @@
struct userlist *userlist = NULL; /* list of all existing userlists */
+#ifdef CONFIG_HAP_CRYPT
+__decl_hathreads(static HA_SPINLOCK_T auth_lock);
+#endif
+
/* find targets for selected gropus. The function returns pointer to
* the userlist struct ot NULL if name is NULL/empty or unresolvable.
*/
@@ -245,7 +250,9 @@ check_user(struct userlist *ul, const char *user, const char *pass)
if (!(u->flags & AU_O_INSECURE)) {
#ifdef CONFIG_HAP_CRYPT
+ HA_SPIN_LOCK(AUTH_LOCK, &auth_lock);
ep = crypt(pass, u->pass);
+ HA_SPIN_UNLOCK(AUTH_LOCK, &auth_lock);
#else
return 0;
#endif
--
2.14.4

118
fix-invalid-addr-calc.patch Normal file
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@ -0,0 +1,118 @@
From 3285ced5cbec5d8a0c3464f1762d34439280f8eb Mon Sep 17 00:00:00 2001
From: Willy Tarreau <w@1wt.eu>
Date: Wed, 11 Mar 2020 11:54:04 +0100
Subject: [PATCH] BUG/MAJOR: list: fix invalid element address calculation
Ryan O'Hara reported that haproxy breaks on fedora-32 using gcc-10
(pre-release). It turns out that constructs such as:
while (item != head) {
item = LIST_ELEM(item.n);
}
loop forever, never matching <item> to <head> despite a printf there
showing them equal. In practice the problem is that the LIST_ELEM()
macro is wrong, it assigns the subtract of two pointers (an integer)
to another pointer through a cast to its pointer type. And GCC 10 now
considers that this cannot match a pointer and silently optimizes the
comparison away. A tested workaround for this is to build with
-fno-tree-pta. Note that older gcc versions even with -ftree-pta do
not exhibit this rather surprizing behavior.
This patch changes the test to instead cast the null-based address to
an int to get the offset and subtract it from the pointer, and this
time it works. There were just a few places to adjust. Ideally
offsetof() should be used but the LIST_ELEM() API doesn't make this
trivial as it's commonly called with a typeof(ptr) and not typeof(ptr*)
thus it would require to completely change the whole API, which is not
something workable in the short term, especially for a backport.
With this change, the emitted code is subtly different even on older
versions. A code size reduction of ~600 bytes and a total executable
size reduction of ~1kB are expected to be observed and should not be
taken as an anomaly. Typically this loop in dequeue_proxy_listeners() :
while ((listener = MT_LIST_POP(...)))
used to produce this code where the comparison is performed on RAX
while the new offset is assigned to RDI even though both are always
identical:
53ded8: 48 8d 78 c0 lea -0x40(%rax),%rdi
53dedc: 48 83 f8 40 cmp $0x40,%rax
53dee0: 74 39 je 53df1b <dequeue_proxy_listeners+0xab>
and now produces this one which is slightly more efficient as the
same register is used for both purposes:
53dd08: 48 83 ef 40 sub $0x40,%rdi
53dd0c: 74 2d je 53dd3b <dequeue_proxy_listeners+0x9b>
Similarly, retrieving the channel from a stream_interface using si_ic()
and si_oc() used to cause this (stream-int in rdi):
1cb7: c7 47 1c 00 02 00 00 movl $0x200,0x1c(%rdi)
1cbe: f6 47 04 10 testb $0x10,0x4(%rdi)
1cc2: 74 1c je 1ce0 <si_report_error+0x30>
1cc4: 48 81 ef 00 03 00 00 sub $0x300,%rdi
1ccb: 81 4f 10 00 08 00 00 orl $0x800,0x10(%rdi)
and now causes this:
1cb7: c7 47 1c 00 02 00 00 movl $0x200,0x1c(%rdi)
1cbe: f6 47 04 10 testb $0x10,0x4(%rdi)
1cc2: 74 1c je 1ce0 <si_report_error+0x30>
1cc4: 81 8f 10 fd ff ff 00 orl $0x800,-0x2f0(%rdi)
There is extremely little chance that this fix wakes up a dormant bug as
the emitted code effectively does what the source code intends.
This must be backported to all supported branches (dropping MT_LIST_ELEM
and the spoa_example parts as needed), since the bug is subtle and may
not always be visible even when compiling with gcc-10.
(cherry picked from commit 855796bdc8b1bc2ebcc697ca99fb304bc6e2abe9)
Signed-off-by: Willy Tarreau <w@1wt.eu>
---
contrib/spoa_example/include/mini-clist.h | 2 +-
include/common/mini-clist.h | 4 ++--
2 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/contrib/spoa_example/include/mini-clist.h b/contrib/spoa_example/include/mini-clist.h
index a89255c46..d009704cc 100644
--- a/contrib/spoa_example/include/mini-clist.h
+++ b/contrib/spoa_example/include/mini-clist.h
@@ -44,7 +44,7 @@ struct list {
* since it's used only once.
* Example: LIST_ELEM(cur_node->args.next, struct node *, args)
*/
-#define LIST_ELEM(lh, pt, el) ((pt)(((void *)(lh)) - ((void *)&((pt)NULL)->el)))
+#define LIST_ELEM(lh, pt, el) ((pt)(((const char *)(lh)) - ((size_t)&((pt)NULL)->el)))
/* checks if the list head <lh> is empty or not */
#define LIST_ISEMPTY(lh) ((lh)->n == (lh))
diff --git a/include/common/mini-clist.h b/include/common/mini-clist.h
index e29451148..01bd0b695 100644
--- a/include/common/mini-clist.h
+++ b/include/common/mini-clist.h
@@ -137,7 +137,7 @@ struct cond_wordlist {
* since it's used only once.
* Example: LIST_ELEM(cur_node->args.next, struct node *, args)
*/
-#define LIST_ELEM(lh, pt, el) ((pt)(((void *)(lh)) - ((void *)&((pt)NULL)->el)))
+#define LIST_ELEM(lh, pt, el) ((pt)(((const char *)(lh)) - ((size_t)&((pt)NULL)->el)))
/* checks if the list head <lh> is empty or not */
#define LIST_ISEMPTY(lh) ((lh)->n == (lh))
@@ -463,7 +463,7 @@ struct cond_wordlist {
* since it's used only once.
* Example: MT_LIST_ELEM(cur_node->args.next, struct node *, args)
*/
-#define MT_LIST_ELEM(lh, pt, el) ((pt)(((void *)(lh)) - ((void *)&((pt)NULL)->el)))
+#define MT_LIST_ELEM(lh, pt, el) ((pt)(((const char *)(lh)) - ((size_t)&((pt)NULL)->el)))
/* checks if the list head <lh> is empty or not */
#define MT_LIST_ISEMPTY(lh) ((lh)->next == (lh))
--
2.24.1

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@ -8,7 +8,7 @@
Name: haproxy Name: haproxy
Version: 2.1.3 Version: 2.1.3
Release: 1%{?dist} Release: 2%{?dist}
Summary: HAProxy reverse proxy for high availability environments Summary: HAProxy reverse proxy for high availability environments
License: GPLv2+ License: GPLv2+
@ -21,6 +21,8 @@ Source3: %{name}.logrotate
Source4: %{name}.sysconfig Source4: %{name}.sysconfig
Source5: halog.1 Source5: halog.1
Patch1: fix-invalid-addr-calc.patch
BuildRequires: gcc BuildRequires: gcc
BuildRequires: lua-devel BuildRequires: lua-devel
BuildRequires: pcre2-devel BuildRequires: pcre2-devel
@ -48,6 +50,7 @@ availability environments. Indeed, it can:
%prep %prep
%setup -q %setup -q
%patch1 -p1
%build %build
regparm_opts= regparm_opts=
@ -132,6 +135,9 @@ exit 0
%{_mandir}/man1/* %{_mandir}/man1/*
%changelog %changelog
* Mon Mar 16 2020 Ryan O'Hara <rohara@redhat.com> - 2.1.3-2
- Fix invalid element address calculation (#1801109)
* Wed Feb 12 2020 Ryan O'Hara <rohara@redhat.com> - 2.1.3-1 * Wed Feb 12 2020 Ryan O'Hara <rohara@redhat.com> - 2.1.3-1
- Update to 2.1.3 (#1802233) - Update to 2.1.3 (#1802233)