This is a note to let you know that I've just added the patch titled
dm snapshot: fix a possible invalid memory access on unload
to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
dm-snapshot-fix-a-possible-invalid-memory-access-on-unload.patch
and it can be found in the queue-3.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 22aa66a3ee5b61e0f4a0bfeabcaa567861109ec3 Mon Sep 17 00:00:00 2001
From: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Date: Tue, 17 Feb 2015 14:34:00 -0500
Subject: dm snapshot: fix a possible invalid memory access on unload
From: Mikulas Patocka <mpatocka@xxxxxxxxxx>
commit 22aa66a3ee5b61e0f4a0bfeabcaa567861109ec3 upstream.
When the snapshot target is unloaded, snapshot_dtr() waits until
pending_exceptions_count drops to zero. Then, it destroys the snapshot.
Therefore, the function that decrements pending_exceptions_count
should not touch the snapshot structure after the decrement.
pending_complete() calls free_pending_exception(), which decrements
pending_exceptions_count, and then it performs up_write(&s->lock) and it
calls retry_origin_bios() which dereferences s->origin. These two
memory accesses to the fields of the snapshot may touch the dm_snapshot
struture after it is freed.
This patch moves the call to free_pending_exception() to the end of
pending_complete(), so that the snapshot will not be destroyed while
pending_complete() is in progress.
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/md/dm-snap.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -1439,8 +1439,6 @@ out:
full_bio->bi_end_io = pe->full_bio_end_io;
full_bio->bi_private = pe->full_bio_private;
}
- free_pending_exception(pe);
-
increment_pending_exceptions_done_count();
up_write(&s->lock);
@@ -1457,6 +1455,8 @@ out:
}
retry_origin_bios(s, origin_bios);
+
+ free_pending_exception(pe);
}
static void commit_callback(void *context, int success)
Patches currently in stable-queue which might be from mpatocka@xxxxxxxxxx are
queue-3.10/dm-snapshot-fix-a-possible-invalid-memory-access-on-unload.patch
queue-3.10/dm-fix-a-race-condition-in-dm_get_md.patch
queue-3.10/dm-mirror-do-not-degrade-the-mirror-on-discard-error.patch
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