On Sat, 3 Jun 2023, Demi Marie Obenour wrote:
Especially on 32-bit systems, it is possible for the pointer arithmetic to overflow and cause a userspace pointer to be dereferenced in the kernel.
Signed-off-by: Demi Marie Obenour demi@invisiblethingslab.com Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org
Reviewed-by: Mikulas Patocka mpatocka@redhat.com
drivers/md/dm-ioctl.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+)
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c index 34fa74c6a70db8aa67aaba3f6a2fc4f38ef736bc..64e8f16d344c47057de5e2d29e3d63202197dca0 100644 --- a/drivers/md/dm-ioctl.c +++ b/drivers/md/dm-ioctl.c @@ -1396,6 +1396,25 @@ static int next_target(struct dm_target_spec *last, uint32_t next, void *end, { static_assert(_Alignof(struct dm_target_spec) <= 8, "struct dm_target_spec has excessive alignment requirements");
- static_assert(offsetof(struct dm_ioctl, data) >= sizeof(struct dm_target_spec),
"struct dm_target_spec too big");- /*
* Number of bytes remaining, starting with last. This is always* sizeof(struct dm_target_spec) or more, as otherwise *last was* out of bounds already.*/- size_t remaining = (char *)end - (char *)last;
- /*
* There must be room for both the next target spec and the* NUL-terminator of the target itself.*/- if (remaining - sizeof(struct dm_target_spec) <= next) {
DMERR("Target spec extends beyond end of parameters");return -EINVAL;- }
- if (next % 8) { DMERR("Next target spec (offset %u) is not 8-byte aligned", next); return -EINVAL;
-- Sincerely, Demi Marie Obenour (she/her/hers) Invisible Things Lab
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