From 18e615ad87bce9125ef3990377a4a946ec0f21f3 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Tue, 13 Dec 2016 13:34:02 +0000 Subject: [PATCH] crypto: skcipher - fix crash in virtual walk The new skcipher walk API may crash in the following way. (Interestingly, the tcrypt boot time tests seem unaffected, while an explicit test using the module triggers it) Unable to handle kernel NULL pointer dereference at virtual address 00000000 ... [] __memcpy+0x84/0x180 [] skcipher_walk_done+0x328/0x340 [] ctr_encrypt+0x84/0x100 [] simd_skcipher_encrypt+0x88/0x98 [] crypto_rfc3686_crypt+0x8c/0x98 [] test_skcipher_speed+0x518/0x820 [tcrypt] [] do_test+0x1408/0x3b70 [tcrypt] [] tcrypt_mod_init+0x50/0x1000 [tcrypt] [] do_one_initcall+0x44/0x138 [] do_init_module+0x68/0x1e0 [] load_module+0x1fd0/0x2458 [] SyS_finit_module+0xe0/0xf0 [] el0_svc_naked+0x24/0x28 This is due to the fact that skcipher_done_slow() may be entered with walk->buffer unset. Since skcipher_walk_done() already deals with the case where walk->buffer == walk->page, it appears to be the intention that walk->buffer point to walk->page after skcipher_next_slow(), so ensure that is the case. Signed-off-by: Ard Biesheuvel Signed-off-by: Herbert Xu --- crypto/skcipher.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/crypto/skcipher.c b/crypto/skcipher.c index aca07c643d41..0e1e6c35188e 100644 --- a/crypto/skcipher.c +++ b/crypto/skcipher.c @@ -226,7 +226,9 @@ static int skcipher_next_slow(struct skcipher_walk *walk, unsigned int bsize) void *v; if (!phys) { - buffer = walk->buffer ?: walk->page; + if (!walk->buffer) + walk->buffer = walk->page; + buffer = walk->buffer; if (buffer) goto ok; }