Hi Mikulas, Thanks for the suggested fix. We verified it on Linux 6.6.144 with KASAN against our minimized PoC (resume racing remove / reboot-notifier UAF).
if (!dm_suspended_md(md) || test_bit(DMF_FREEING, &md->flags)) goto out; Results: - unpatched: KASAN slab-use-after-free in notifier_chain_register via dm_integrity_resume within ~20s - with your change: no KASAN UAF for a 5-minute PoC window Self-contained test package (patch + poc.c + A/B scripts + captured logs): dm-integrity-dm-resume-fix-test.tar.gz Re-run with Docker (see README.md inside the tarball): docker build -t dm-integrity-patch-test -f Dockerfile . mkdir -p artifacts docker run --rm --privileged --device=/dev/kvm --network=host \ -v "$PWD/artifacts:/artifacts" -e OUTPUT_DIR=/artifacts \ dm-integrity-patch-test Thanks, Junzhe On 7/23/2026 12:14 AM, Mikulas Patocka wrote:
On Sat, 18 Jul 2026, Junzhe Yu wrote:Hello, I am reporting a KASAN slab use-after-free in dm-integrity involving the reboot notifier registration path. Summary ======= A late do_resume() can register ic->reboot_notifier on a dm_integrity_c object that a concurrent DM_DEV_REMOVE path is destroying. The removal path unregisters the old notifier via dm_integrity_postsuspend() and later frees ic in dm_integrity_dtr(), but does not unregister the notifier that the racing resume just installed. The global reboot notifier chain is then left with a dangling node; a later notifier_chain_register() walk touches it and panics under KASAN.Hi Does this patch fix it? Mikulas dm: fix resume-vs-remove race If the user issues the resume ioctl and the remove ioctl at the same time, it may be possible that the device is resumed after it is suspended in __dm_destroy. The result is that the table is destroyed without calling the postsuspend method. Dm targets expect that they may be removed only after the postsuspend method method was called. If we break this expectation, it can cause misbehavior in various targets. For example - in the dm-integrity target, the reboot notifier is not unregistered, leading to use-after-free. Fix this bug by refusing to resume if the device is being destroyed. Signed-off-by: Mikulas Patocka <[email protected]> Cc: [email protected] --- drivers/md/dm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) Index: linux-2.6/drivers/md/dm.c =================================================================== --- linux-2.6.orig/drivers/md/dm.c 2026-07-13 20:58:56.000000000 +0200 +++ linux-2.6/drivers/md/dm.c 2026-07-22 17:40:29.000000000 +0200 @@ -3140,7 +3140,7 @@ retry: r = -EINVAL; mutex_lock_nested(&md->suspend_lock, SINGLE_DEPTH_NESTING);- if (!dm_suspended_md(md))+ if (!dm_suspended_md(md) || test_bit(DMF_FREEING, &md->flags)) goto out;if (dm_suspended_internally_md(md)) {
dm-integrity-dm-resume-fix-test.tar.gz
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