On Thu, Mar 05, 2020 at 04:57:55PM +0800, yangerkun wrote:
Nowdays, we trigger a oops: ... kasan: GPF could be caused by NULL-ptr deref or user memory accessgeneral protection fault: 0000 [#1] SMP KASAN ... Call Trace: [<ffffffff81a26fb1>] skcipher_recvmsg_async+0x3f1/0x1400 x86/../crypto/algif_skcipher.c:543 [<ffffffff81a28053>] skcipher_recvmsg+0x93/0x7f0 x86/../crypto/algif_skcipher.c:723 [<ffffffff823e43a4>] sock_recvmsg_nosec x86/../net/socket.c:702 [inline] [<ffffffff823e43a4>] sock_recvmsg x86/../net/socket.c:710 [inline] [<ffffffff823e43a4>] sock_recvmsg+0x94/0xc0 x86/../net/socket.c:705 [<ffffffff823e464b>] sock_read_iter+0x27b/0x3a0 x86/../net/socket.c:787 [<ffffffff817f479b>] aio_run_iocb+0x21b/0x7a0 x86/../fs/aio.c:1520 [<ffffffff817f57c9>] io_submit_one x86/../fs/aio.c:1630 [inline] [<ffffffff817f57c9>] do_io_submit+0x6b9/0x10b0 x86/../fs/aio.c:1688 [<ffffffff817f902d>] SYSC_io_submit x86/../fs/aio.c:1713 [inline] [<ffffffff817f902d>] SyS_io_submit+0x2d/0x40 x86/../fs/aio.c:1710 [<ffffffff828b33c3>] tracesys_phase2+0x90/0x95
In skcipher_recvmsg_async, we use '!sreq->tsg' to determine does we calloc fail. However, kcalloc may return ZERO_SIZE_PTR, and with this, the latter sg_init_table will trigger the bug. Fix it be use ZERO_OF_NULL_PTR.
This function was introduced with ' commit a596999b7ddf ("crypto: algif - change algif_skcipher to be asynchronous")', and has been removed with 'commit e870456d8e7c ("crypto: algif_skcipher - overhaul memory management")'.
Reported-by: Hulk Robot hulkci@huawei.com Signed-off-by: yangerkun yangerkun@huawei.com
crypto/algif_skcipher.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
v1->v2: update the commit message
diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c index d12782dc9683..9bd4691cc5c5 100644 --- a/crypto/algif_skcipher.c +++ b/crypto/algif_skcipher.c @@ -538,7 +538,7 @@ static int skcipher_recvmsg_async(struct socket *sock, struct msghdr *msg, lock_sock(sk); tx_nents = skcipher_all_sg_nents(ctx); sreq->tsg = kcalloc(tx_nents, sizeof(*sg), GFP_KERNEL);
- if (unlikely(!sreq->tsg))
- if (unlikely(ZERO_OR_NULL_PTR(sreq->tsg)))
I'm a bit confused: kcalloc() will return ZERO_SIZE_PTR for allocations that ask for 0 bytes, but here we ask for "sizeof(*sg)" bytes, which is guaranteed to be more than 0, no?