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Overwrite target for x86_64_v2

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Update patch-git.lua to handle AlmaLinux branches correctly
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Eduard Abdullin 2025-12-09 01:41:20 +00:00 committed by root
commit 502ea0e9d6
2 changed files with 59 additions and 1 deletions
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58
glibc-RHEL-119398.patch Normal file
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@ -0,0 +1,58 @@
commit 6c915c73d08028987232f6dc718f218c61113240
Author: Aurelien Jarno <aurelien@aurel32.net>
Date: Sun Nov 10 10:50:34 2024 +0100
elf: handle addition overflow in _dl_find_object_update_1 [BZ #32245]
The remaining_to_add variable can be 0 if (current_used + count) wraps,
This is caught by GCC 14+ on hppa, which determines from there that
target_seg could be be NULL when remaining_to_add is zero, which in
turns causes a -Wstringop-overflow warning:
In file included from ../include/atomic.h:49,
from dl-find_object.c:20:
In function '_dlfo_update_init_seg',
inlined from '_dl_find_object_update_1' at dl-find_object.c:689:30,
inlined from '_dl_find_object_update' at dl-find_object.c:805:13:
../sysdeps/unix/sysv/linux/hppa/atomic-machine.h:44:4: error: '__atomic_store_4' writing 4 bytes into a region of size 0 overflows the destination [-Werror=stringop-overflow=]
44 | __atomic_store_n ((mem), (val), __ATOMIC_RELAXED); \
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
dl-find_object.c:644:3: note: in expansion of macro 'atomic_store_relaxed'
644 | atomic_store_relaxed (&seg->size, new_seg_size);
| ^~~~~~~~~~~~~~~~~~~~
In function '_dl_find_object_update':
cc1: note: destination object is likely at address zero
In practice, this is not possible as it represent counts of link maps.
Link maps have sizes larger than 1 byte, so the sum of any two link map
counts will always fit within a size_t without wrapping around.
This patch therefore adds a check on remaining_to_add == 0 and tell GCC
that this can not happen using __builtin_unreachable.
Thanks to Andreas Schwab for the investigation.
Closes: BZ #32245
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Tested-by: John David Anglin <dave.anglin@bell.net>
Reviewed-by: Florian Weimer <fweimer@redhat.com>
diff --git a/elf/dl-find_object.c b/elf/dl-find_object.c
index 449302eda3..ae18b438d3 100644
--- a/elf/dl-find_object.c
+++ b/elf/dl-find_object.c
@@ -682,6 +682,14 @@ _dl_find_object_update_1 (struct link_map **loaded, size_t count)
= _dlfo_loaded_mappings[!active_idx];
size_t remaining_to_add = current_used + count;
+ /* remaining_to_add can be 0 if (current_used + count) wraps, but in practice
+ this is not possible as it represent counts of link maps. Link maps have
+ sizes larger than 1 byte, so the sum of any two link map counts will
+ always fit within a size_t without wrapping around. This check ensures
+ that target_seg is not erroneously considered potentially NULL by GCC. */
+ if (remaining_to_add == 0)
+ __builtin_unreachable ();
+
/* Ensure that the new segment chain has enough space. */
{
size_t new_allocated

2
glibc.spec
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@ -2357,7 +2357,7 @@ update_gconv_modules_cache ()
%endif
%changelog
* Mon Dec 08 2025 Eduard Abdullin <eabdullin@almalinux.org> - 2.39-104.alma.1
* Tue Dec 09 2025 Eduard Abdullin <eabdullin@almalinux.org> - 2.39-105.alma.1
- Overwrite target for x86_64_v2
- Update patch-git.lua to handle AlmaLinux branches correctly