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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 | |
| parent | 4495c08e84729385774601b5146d51d9e5849f81 (diff) | |
| download | blackbird-obmc-linux-f1a880a93baaadb14c10a348fd199f1cdb6bcccd.tar.gz blackbird-obmc-linux-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')
| -rw-r--r-- | drivers/md/dm-verity-fec.c | 12 | ||||
| -rw-r--r-- | drivers/md/dm-verity-fec.h | 4 |
2 files changed, 15 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; } /* diff --git a/drivers/md/dm-verity-fec.h b/drivers/md/dm-verity-fec.h index 7fa0298b995e..bb31ce87a933 100644 --- a/drivers/md/dm-verity-fec.h +++ b/drivers/md/dm-verity-fec.h @@ -27,6 +27,9 @@ #define DM_VERITY_FEC_BUF_MAX \ (1 << (PAGE_SHIFT - DM_VERITY_FEC_BUF_RS_BITS)) +/* maximum recursion level for verity_fec_decode */ +#define DM_VERITY_FEC_MAX_RECURSION 4 + #define DM_VERITY_OPT_FEC_DEV "use_fec_from_device" #define DM_VERITY_OPT_FEC_BLOCKS "fec_blocks" #define DM_VERITY_OPT_FEC_START "fec_start" @@ -58,6 +61,7 @@ struct dm_verity_fec_io { unsigned nbufs; /* number of buffers allocated */ u8 *output; /* buffer for corrected output */ size_t output_pos; + unsigned level; /* recursion level */ }; #ifdef CONFIG_DM_VERITY_FEC |
