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| author |   Sami Tolvanen <samitolvanen@google.com> | 2017-03-15 15:12:23 -0700 |
|---|---|---|
| committer |   Mike Snitzer <snitzer@redhat.com> | 2017-03-16 09:37:31 -0400 |
| commit | f1a880a93baaadb14c10a348fd199f1cdb6bcccd (patch) | |
| tree | c2ce582e5337e48033a5c56ded2435f9759e5f2a /drivers/md/dm-verity-fec.c | |
| parent | Linux 4.11-rc2 (diff) | |
| download | linux-dev-f1a880a93baaadb14c10a348fd199f1cdb6bcccd.tar.xz linux-dev-f1a880a93baaadb14c10a348fd199f1cdb6bcccd.zip | |
dm verity fec: limit error correction recursion
If the hash tree itself is sufficiently corrupt in addition to data blocks,
it's possible for error correction to end up in a deep recursive loop,
which eventually causes a kernel panic. This change limits the
recursion to a reasonable level during a single I/O operation.
Fixes: a739ff3f543a ("dm verity: add support for forward error correction")
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org # v4.5+
Diffstat (limited to 'drivers/md/dm-verity-fec.c')
| -rw-r--r-- | drivers/md/dm-verity-fec.c | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/drivers/md/dm-verity-fec.c b/drivers/md/dm-verity-fec.c index 0f0eb8a3d922..c3cc04d89524 100644 --- a/drivers/md/dm-verity-fec.c +++ b/drivers/md/dm-verity-fec.c @@ -439,6 +439,13 @@ 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; @@ -470,7 +477,7 @@ 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) @@ -480,6 +487,8 @@ 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; } @@ -520,6 +529,7 @@ void verity_fec_init_io(struct dm_verity_io *io) memset(fio->bufs, 0, sizeof(fio->bufs)); fio->nbufs = 0; fio->output = NULL; + fio->level = 0; } /* |