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| author | Mikulas Patocka <mpatocka@redhat.com> | 2018-09-05 09:17:45 -0400 |
|---|---|---|
| committer | Mike Snitzer <snitzer@redhat.com> | 2018-09-06 13:31:09 -0400 |
| commit | 432061b3da64e488be3403124a72a9250bbe96d4 (patch) | |
| tree | 62cf9d433b59092b20daa55897dc60827940cbff /drivers/md/dm-integrity.c | |
| parent | e4b069e0945fa14c71cf8b5b89f8b1b2aa68dbc2 (diff) | |
| download | linux-stable-432061b3da64e488be3403124a72a9250bbe96d4.tar.gz linux-stable-432061b3da64e488be3403124a72a9250bbe96d4.tar.bz2 linux-stable-432061b3da64e488be3403124a72a9250bbe96d4.zip | |
dm: disable CRYPTO_TFM_REQ_MAY_SLEEP to fix a GFP_KERNEL recursion deadlock
There's a XFS on dm-crypt deadlock, recursing back to itself due to the
crypto subsystems use of GFP_KERNEL, reported here:
https://bugzilla.kernel.org/show_bug.cgi?id=200835
* dm-crypt calls crypt_convert in xts mode
* init_crypt from xts.c calls kmalloc(GFP_KERNEL)
* kmalloc(GFP_KERNEL) recurses into the XFS filesystem, the filesystem
tries to submit some bios and wait for them, causing a deadlock
Fix this by updating both the DM crypt and integrity targets to no
longer use the CRYPTO_TFM_REQ_MAY_SLEEP flag, which will change the
crypto allocations from GFP_KERNEL to GFP_ATOMIC, therefore they can't
recurse into a filesystem. A GFP_ATOMIC allocation can fail, but
init_crypt() in xts.c handles the allocation failure gracefully - it
will fall back to preallocated buffer if the allocation fails.
The crypto API maintainer says that the crypto API only needs to
allocate memory when dealing with unaligned buffers and therefore
turning CRYPTO_TFM_REQ_MAY_SLEEP off is safe (see this discussion:
https://www.redhat.com/archives/dm-devel/2018-August/msg00195.html )
Cc: stable@vger.kernel.org
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md/dm-integrity.c')
| -rw-r--r-- | drivers/md/dm-integrity.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c index 378878599466..89ccb64342de 100644 --- a/drivers/md/dm-integrity.c +++ b/drivers/md/dm-integrity.c @@ -532,7 +532,7 @@ static void section_mac(struct dm_integrity_c *ic, unsigned section, __u8 result unsigned j, size; desc->tfm = ic->journal_mac; - desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP; + desc->flags = 0; r = crypto_shash_init(desc); if (unlikely(r)) { @@ -676,7 +676,7 @@ static void complete_journal_encrypt(struct crypto_async_request *req, int err) static bool do_crypt(bool encrypt, struct skcipher_request *req, struct journal_completion *comp) { int r; - skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP, + skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG, complete_journal_encrypt, comp); if (likely(encrypt)) r = crypto_skcipher_encrypt(req); |