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| author | Sami Tolvanen <samitolvanen@google.com> | 2016-06-03 14:06:14 -0700 |
|---|---|---|
| committer | Amit Pundir <amit.pundir@linaro.org> | 2016-06-16 13:44:10 +0530 |
| commit | 69c5db92e4726042c3b4bb6a336fb2bce0995e52 (patch) | |
| tree | 817a532bd1e567ef296811400a08bd779c52566e /drivers/md/dm-verity-fec.c | |
| parent | 377fd8e3af2c1f74b51817032fcbe6c06e49ea7e (diff) | |
ANDROID: dm verity fec: limit error correction recursion
If verity tree itself is sufficiently corrupted in addition to data
blocks, it's possible for error correction to end up in a deep recursive
error correction loop that eventually causes a kernel panic as follows:
[ 14.728962] [<ffffffc0008c1a14>] verity_fec_decode+0xa8/0x138
[ 14.734691] [<ffffffc0008c3ee0>] verity_verify_level+0x11c/0x180
[ 14.740681] [<ffffffc0008c482c>] verity_hash_for_block+0x88/0xe0
[ 14.746671] [<ffffffc0008c1508>] fec_decode_rsb+0x318/0x75c
[ 14.752226] [<ffffffc0008c1a14>] verity_fec_decode+0xa8/0x138
[ 14.757956] [<ffffffc0008c3ee0>] verity_verify_level+0x11c/0x180
[ 14.763944] [<ffffffc0008c482c>] verity_hash_for_block+0x88/0xe0
This change limits the recursion to a reasonable level during a single
I/O operation.
Bug: 28943429
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Change-Id: I0a7ebff331d259c59a5e03c81918cc1613c3a766
(cherry picked from commit f4b9e40597e73942d2286a73463c55f26f61bfa7)
Diffstat (limited to 'drivers/md/dm-verity-fec.c')
| -rw-r--r-- | drivers/md/dm-verity-fec.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/drivers/md/dm-verity-fec.c b/drivers/md/dm-verity-fec.c index ad10d6d8ed28..b26809a47ca3 100644 --- a/drivers/md/dm-verity-fec.c +++ b/drivers/md/dm-verity-fec.c @@ -442,6 +442,13 @@ int verity_fec_decode(struct dm_verity *v, struct dm_verity_io *io, if (!verity_fec_is_enabled(v)) return -EOPNOTSUPP; + if (fio->level >= DM_VERITY_FEC_MAX_RECURSION) { + DMWARN_LIMIT("%s: FEC: recursion too deep", v->data_dev->name); + return -EIO; + } + + fio->level++; + if (type == DM_VERITY_BLOCK_TYPE_METADATA) block += v->data_blocks; @@ -475,7 +482,7 @@ int verity_fec_decode(struct dm_verity *v, struct dm_verity_io *io, if (r < 0) { r = fec_decode_rsb(v, io, fio, rsb, offset, true); if (r < 0) - return r; + goto done; } if (dest) @@ -485,6 +492,8 @@ int verity_fec_decode(struct dm_verity *v, struct dm_verity_io *io, r = verity_for_bv_block(v, io, iter, fec_bv_copy); } +done: + fio->level--; return r; } |