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H A D | dm-snap.c | c699a0db Mon May 10 13:49:05 CDT 2021 Mikulas Patocka <mpatocka@redhat.com> dm snapshot: fix crash with transient storage and zero chunk size
The following commands will crash the kernel:
modprobe brd rd_size=1048576 dmsetup create o --table "0 `blockdev --getsize /dev/ram0` snapshot-origin /dev/ram0" dmsetup create s --table "0 `blockdev --getsize /dev/ram0` snapshot /dev/ram0 /dev/ram1 N 0"
The reason is that when we test for zero chunk size, we jump to the label bad_read_metadata without setting the "r" variable. The function snapshot_ctr destroys all the structures and then exits with "r == 0". The kernel then crashes because it falsely believes that snapshot_ctr succeeded.
In order to fix the bug, we set the variable "r" to -EINVAL.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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