68 lines
3.0 KiB
Diff
68 lines
3.0 KiB
Diff
From a6c758229e79375efcbf4b30a68cd8c24b48e88f Mon Sep 17 00:00:00 2001
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From: Phil Sutter <phil@nwl.cc>
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Date: Fri, 7 Oct 2022 18:29:07 +0200
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Subject: [PATCH] libiptc: Fix for segfault when renaming a chain
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This is an odd bug: If the number of chains is right and one renames the
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last one in the list, libiptc dereferences a NULL pointer. Add fix and
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test case for it.
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Fixes: 64ff47cde38e4 ("libiptc: fix chain rename bug in libiptc")
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Reported-by: Julien Castets <castets.j@gmail.com>
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Signed-off-by: Phil Sutter <phil@nwl.cc>
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(cherry picked from commit 97bf4e68fc0794adba3243fd96f40f4568e7216f)
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---
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.../testcases/chain/0006rename-segfault_0 | 19 +++++++++++++++++++
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libiptc/libiptc.c | 9 +++++++++
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2 files changed, 28 insertions(+)
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create mode 100755 iptables/tests/shell/testcases/chain/0006rename-segfault_0
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diff --git a/iptables/tests/shell/testcases/chain/0006rename-segfault_0 b/iptables/tests/shell/testcases/chain/0006rename-segfault_0
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new file mode 100755
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index 0000000000000..c10a8006b56b4
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--- /dev/null
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+++ b/iptables/tests/shell/testcases/chain/0006rename-segfault_0
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@@ -0,0 +1,19 @@
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+#!/bin/bash
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+#
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+# Cover for a bug in libiptc:
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+# - the chain 'node-98-tmp' is the last in the list sorted by name
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+# - there are 81 chains in total, so three chain index buckets
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+# - the last index bucket contains only the 'node-98-tmp' chain
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+# => rename temporarily removes it from the bucket, leaving a NULL bucket
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+# behind which is dereferenced later when inserting the chain again with new
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+# name again
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+
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+(
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+ echo "*filter"
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+ for chain in node-1 node-10 node-101 node-102 node-104 node-107 node-11 node-12 node-13 node-14 node-15 node-16 node-17 node-18 node-19 node-2 node-20 node-21 node-22 node-23 node-25 node-26 node-27 node-28 node-29 node-3 node-30 node-31 node-32 node-33 node-34 node-36 node-37 node-39 node-4 node-40 node-41 node-42 node-43 node-44 node-45 node-46 node-47 node-48 node-49 node-5 node-50 node-51 node-53 node-54 node-55 node-56 node-57 node-58 node-59 node-6 node-60 node-61 node-62 node-63 node-64 node-65 node-66 node-68 node-69 node-7 node-70 node-71 node-74 node-75 node-76 node-8 node-80 node-81 node-86 node-89 node-9 node-92 node-93 node-95 node-98-tmp; do
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+ echo ":$chain - [0:0]"
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+ done
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+ echo "COMMIT"
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+) | $XT_MULTI iptables-restore
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+$XT_MULTI iptables -E node-98-tmp node-98
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+exit $?
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diff --git a/libiptc/libiptc.c b/libiptc/libiptc.c
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index 5888201525213..56bb75e5c3bef 100644
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--- a/libiptc/libiptc.c
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+++ b/libiptc/libiptc.c
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@@ -606,6 +606,15 @@ static int iptcc_chain_index_delete_chain(struct chain_head *c, struct xtc_handl
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if (index_ptr == &c->list) { /* Chain used as index ptr */
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+ /* If this is the last chain in the list, its index bucket just
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+ * became empty. Adjust the size to avoid a NULL-pointer deref
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+ * later.
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+ */
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+ if (next == &h->chains) {
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+ h->chain_index_sz--;
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+ return 0;
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+ }
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+
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/* See if its possible to avoid a rebuild, by shifting
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* to next pointer. Its possible if the next pointer
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* is located in the same index bucket.
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--
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2.40.0
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