summaryrefslogtreecommitdiff
path: root/drivers/md
diff options
context:
space:
mode:
authorSami Tolvanen <samitolvanen@google.com>2017-03-15 15:12:23 -0700
committerMike Snitzer <snitzer@redhat.com>2017-03-16 09:37:31 -0400
commitf1a880a93baaadb14c10a348fd199f1cdb6bcccd (patch)
treec2ce582e5337e48033a5c56ded2435f9759e5f2a /drivers/md
parent4495c08e84729385774601b5146d51d9e5849f81 (diff)
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.c12
-rw-r--r--drivers/md/dm-verity-fec.h4
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