There are cases when cryptlen can be zero in crypto_ccm_auth(): -encryptiom: input scatterlist length is zero (no plaintext) -decryption: input scatterlist contains only the mac plus the condition of having different source and destination buffers (or else scatterlist length = max(plaintext_len, ciphertext_len)). These are not handled correctly, leading to crashes like: root@p4080ds:~/crypto# insmod tcrypt.ko mode=45 ------------[ cut here ]------------ kernel BUG at crypto/scatterwalk.c:37! Oops: Exception in kernel mode, sig: 5 [#1] SMP NR_CPUS=8 P4080 DS Modules linked in: tcrypt(+) crc32c xts xcbc vmac pcbc ecb gcm ghash_generic gf128mul ccm ctr seqiv CPU: 3 PID: 1082 Comm: cryptomgr_test Not tainted 3.11.0 #14 task: ee12c5b0 ti: eecd0000 task.ti: eecd0000 NIP: c0204d98 LR: f9225848 CTR: c0204d80 REGS: eecd1b70 TRAP: 0700 Not tainted (3.11.0) MSR: 00029002 <CE,EE,ME> CR: 22044022 XER: 20000000 GPR00: f9225c94 eecd1c20 ee12c5b0 eecd1c28 ee879400 ee879400 00000000 ee607464 GPR08: 00000001 00000001 00000000 006b0000 c0204d80 00000000 00000002 c0698e20 GPR16: ee987000 ee895000 fffffff4 ee879500 00000100 eecd1d58 00000001 00000000 GPR24: ee879400 00000020 00000000 00000000 ee5b2800 ee607430 00000004 ee607460 NIP [c0204d98] scatterwalk_start+0x18/0x30 LR [f9225848] get_data_to_compute+0x28/0x2f0 [ccm] Call Trace: [eecd1c20] [f9225974] get_data_to_compute+0x154/0x2f0 [ccm] (unreliable) [eecd1c70] [f9225c94] crypto_ccm_auth+0x184/0x1d0 [ccm] [eecd1cb0] [f9225d40] crypto_ccm_encrypt+0x60/0x2d0 [ccm] [eecd1cf0] [c020d77c] __test_aead+0x3ec/0xe20 [eecd1e20] [c020f35c] test_aead+0x6c/0xe0 [eecd1e40] [c020f420] alg_test_aead+0x50/0xd0 [eecd1e60] [c020e5e4] alg_test+0x114/0x2e0 [eecd1ee0] [c020bd1c] cryptomgr_test+0x4c/0x60 [eecd1ef0] [c0047058] kthread+0xa8/0xb0 [eecd1f40] [c000eb0c] ret_from_kernel_thread+0x5c/0x64 Instruction dump: 0f080000 81290024 552807fe 0f080000 5529003a 4bffffb4 90830000 39400000 39000001 8124000c 2f890000 7d28579e <0f090000> 81240008 91230004 4e800020 ---[ end trace 6d652dfcd1be37bd ]--- Cc: <stable@xxxxxxxxxxxxxxx> Cc: Jussi Kivilinna <jussi.kivilinna@xxxxxxxx> Signed-off-by: Horia Geanta <horia.geanta@xxxxxxxxxxxxx> --- crypto/ccm.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/crypto/ccm.c b/crypto/ccm.c index 3e05499..1df8421 100644 --- a/crypto/ccm.c +++ b/crypto/ccm.c @@ -271,7 +271,8 @@ static int crypto_ccm_auth(struct aead_request *req, struct scatterlist *plain, } /* compute plaintext into mac */ - get_data_to_compute(cipher, pctx, plain, cryptlen); + if (cryptlen) + get_data_to_compute(cipher, pctx, plain, cryptlen); out: return err; -- 1.7.7.6 -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
