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[v4,06/14] dm verity fec: Remove VLA usage

Message ID 20180711203619.1020-7-keescook@chromium.org (mailing list archive)
State Not Applicable, archived
Delegated to: Mike Snitzer
Headers show

Commit Message

Kees Cook July 11, 2018, 8:36 p.m. UTC 
In the quest to remove all stack VLA usage from the kernel[1], this
uses the newly defined max digest size macro. Also adds a sanity-check
at use-time.

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com

Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/md/dm-verity-fec.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
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Patch

diff --git a/drivers/md/dm-verity-fec.c b/drivers/md/dm-verity-fec.c
index 684af08d0747..fe5cfd1a5fa5 100644
--- a/drivers/md/dm-verity-fec.c
+++ b/drivers/md/dm-verity-fec.c
@@ -212,12 +212,15 @@  static int fec_read_bufs(struct dm_verity *v, struct dm_verity_io *io,
 	struct dm_verity_fec_io *fio = fec_io(io);
 	u64 block, ileaved;
 	u8 *bbuf, *rs_block;
-	u8 want_digest[v->digest_size];
+	u8 want_digest[AHASH_MAX_DIGESTSIZE];
 	unsigned n, k;
 
 	if (neras)
 		*neras = 0;
 
+	if (WARN_ON(v->digest_size > sizeof(want_digest)))
+		return -EINVAL;
+
 	/*
 	 * read each of the rsn data blocks that are part of the RS block, and
 	 * interleave contents to available bufs