On Wed, Sep 09, 2026 at 12:47:21AM +0000, [email protected] wrote:
Thank you for your contribution! Sashiko AI review found 2 potential issue(s)
to consider:
New issues:
- [High] Severe locking imbalance in `crash_load_dm_crypt_keys()` leads to a
leaked mutex on the error path and unlocking an unacquired mutex on the success
path.
Thanks for catching this issue! I'll address it in new version.
Pre-existing issues:
- [High] Premature and unconditional reset of `is_dm_key_reused` to false
breaks ARM64/LoongArch kexec load retries and defeats intended cleanup logic.
--
commit a9405cf8948ba39213612c61a1f3b10b23f437e4
Author: Coiby Xu <[email protected]>
crash_dump: Disallow writing to dm-crypt configfs during kexec_file_load syscall
This commit prevents concurrent writes to the configfs group during the
kexec_file_load syscall by utilizing config_keys_subsys.su_mutex. It aims to
avoid buffer overflows, stale keys, or memory leaks caused by changes to
dm-crypt keys during iteration.
diff --git a/kernel/crash_dump_dm_crypt.c b/kernel/crash_dump_dm_crypt.c
index 3a416933979f8..580534d43b66e 100644
--- a/kernel/crash_dump_dm_crypt.c
+++ b/kernel/crash_dump_dm_crypt.c
[ ... ]
@@ -478,6 +490,9 @@ int crash_load_dm_crypt_keys(struct kimage *image)
"Loaded dm crypt keys to kexec_buffer bufsz=0x%lx
memsz=0x%lx\n",
kbuf.bufsz, kbuf.memsz);
+unlock:
+ mutex_unlock(&config_keys_subsys.su_mutex);
+
[Severity: High]
Looking at crash_load_dm_crypt_keys(), if kexec_add_buffer() fails earlier
in the function, it jumps to the out label, bypassing this unlock label.
Does this leak the config_keys_subsys.su_mutex if the lock was acquired?
Also, on the success path, mutex_unlock() is executed unconditionally. If
is_dm_key_reused was true at the top of the function, the mutex was never
acquired. Can this cause a kernel panic or corruption by unlocking an
unacquired mutex?
out:
- return r;
+ is_dm_key_reused = false;
+ return r;
}
[Severity: High]
This is a pre-existing issue, but since the error and success paths
unconditionally reset is_dm_key_reused to false here, does this break
architectures like ARM64 that might retry segment loading?
If load_other_segments() retries the load sequence, the second pass
through crash_load_dm_crypt_keys() will see is_dm_key_reused as false,
find zero keys, and silently load nothing into the kdump kernel.
Additionally, crash_dm_crypt_cleanup() checks !is_dm_key_reused to determine
whether it should free keys_header. Since the flag is unconditionally cleared
here first, does this defeat the intended cleanup protection logic?
--
Sashiko AI review ยท
https://sashiko.dev/#/patchset/[email protected]?part=3
--
Best regards,
Coiby
