[syzbot] [crypto?] general protection fault in shash_ahash_update

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 9a94d764e9bc Merge tag 'mlx5-updates-2023-06-16' of git://..
git tree: net-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=14774987280000
kernel config: https://syzkaller.appspot.com/x/.config?x=a4a7d74e6a7c3211
dashboard link: https://syzkaller.appspot.com/bug?extid=88f4b1e6cf88da11f5cd
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1152c4ff280000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1307cbcf280000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/79cfaaedcd27/disk-9a94d764.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a22e22124e0b/vmlinux-9a94d764.xz
kernel image: https://storage.googleapis.com/syzbot-assets/fe2e1ce58898/bzImage-9a94d764.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+88f4b1...@syzkaller.appspotmail.com

general protection fault, probably for non-canonical address 0xdffffc0000000004: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000020-0x0000000000000027]
CPU: 1 PID: 5004 Comm: syz-executor202 Not tainted 6.4.0-rc6-syzkaller-01333-g9a94d764e9bc #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
RIP: 0010:crypto_shash_alg include/crypto/hash.h:827 [inline]
RIP: 0010:crypto_shash_update crypto/shash.c:124 [inline]
RIP: 0010:shash_ahash_update+0x126/0x210 crypto/shash.c:306
Code: 8c 00 00 00 e8 bb f7 a4 fd 48 8b 04 24 48 8b 6c 24 40 80 38 00 0f 85 c3 00 00 00 4d 8b 75 00 49 8d 7e 20 48 89 fa 48 c1 ea 03 <80> 3c 1a 00 0f 85 c1 00 00 00 4d 8b 7e 20 49 8d 7f 2c 48 89 fa 48
RSP: 0018:ffffc900039df948 EFLAGS: 00010202
RAX: ffffed1003ce8b6b RBX: dffffc0000000000 RCX: 0000000000000000
RDX: 0000000000000004 RSI: ffffffff83df4f25 RDI: 0000000000000020
RBP: ffff8880732a3100 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000f00 R11: 0000000000000009 R12: 0000000000000f00
R13: ffff88801e745b58 R14: 0000000000000000 R15: 1ffff9200073bf2b
FS: 00005555565db300(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fccb3501440 CR3: 0000000021e60000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
ghash_async_update+0x136/0x170 arch/x86/crypto/ghash-clmulni-intel_glue.c:206
crypto_ahash_update include/crypto/hash.h:608 [inline]
hash_sendmsg+0x434/0xde0 crypto/algif_hash.c:139
sock_sendmsg_nosec net/socket.c:724 [inline]
sock_sendmsg+0xde/0x190 net/socket.c:747
____sys_sendmsg+0x733/0x920 net/socket.c:2493
___sys_sendmsg+0x110/0x1b0 net/socket.c:2547
__sys_sendmsg+0xf7/0x1c0 net/socket.c:2576
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f95e272ecb9
Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd82939a68 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f95e272ecb9
RDX: 0000000000000000 RSI: 00000000200001c0 RDI: 0000000000000004
RBP: 00007f95e26f2e60 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f95e26f2ef0
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:crypto_shash_alg include/crypto/hash.h:827 [inline]
RIP: 0010:crypto_shash_update crypto/shash.c:124 [inline]
RIP: 0010:shash_ahash_update+0x126/0x210 crypto/shash.c:306
Code: 8c 00 00 00 e8 bb f7 a4 fd 48 8b 04 24 48 8b 6c 24 40 80 38 00 0f 85 c3 00 00 00 4d 8b 75 00 49 8d 7e 20 48 89 fa 48 c1 ea 03 <80> 3c 1a 00 0f 85 c1 00 00 00 4d 8b 7e 20 49 8d 7f 2c 48 89 fa 48
RSP: 0018:ffffc900039df948 EFLAGS: 00010202
RAX: ffffed1003ce8b6b RBX: dffffc0000000000 RCX: 0000000000000000
RDX: 0000000000000004 RSI: ffffffff83df4f25 RDI: 0000000000000020
RBP: ffff8880732a3100 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000f00 R11: 0000000000000009 R12: 0000000000000f00
R13: ffff88801e745b58 R14: 0000000000000000 R15: 1ffff9200073bf2b
FS: 00005555565db300(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f29a2df2304 CR3: 0000000021e60000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 8c 00 mov %es,(%rax)
2: 00 00 add %al,(%rax)
4: e8 bb f7 a4 fd callq 0xfda4f7c4
9: 48 8b 04 24 mov (%rsp),%rax
d: 48 8b 6c 24 40 mov 0x40(%rsp),%rbp
12: 80 38 00 cmpb $0x0,(%rax)
15: 0f 85 c3 00 00 00 jne 0xde
1b: 4d 8b 75 00 mov 0x0(%r13),%r14
1f: 49 8d 7e 20 lea 0x20(%r14),%rdi
23: 48 89 fa mov %rdi,%rdx
26: 48 c1 ea 03 shr $0x3,%rdx
* 2a: 80 3c 1a 00 cmpb $0x0,(%rdx,%rbx,1) <-- trapping instruction
2e: 0f 85 c1 00 00 00 jne 0xf5
34: 4d 8b 7e 20 mov 0x20(%r14),%r15
38: 49 8d 7f 2c lea 0x2c(%r15),%rdi
3c: 48 89 fa mov %rdi,%rdx
3f: 48 rex.W


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the bug is already fixed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

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(See the list of subsystem names on the web dashboard)

If the bug is a duplicate of another bug, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

[syzbot]

syzbot has bisected this issue to:

commit c662b043cdca89bf0f03fc37251000ac69a3a548
Author: David Howells <dhow...@redhat.com>
Date: Tue Jun 6 13:08:56 2023 +0000

crypto: af_alg/hash: Support MSG_SPLICE_PAGES

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=14a7cbcf280000
start commit: 9a94d764e9bc Merge tag 'mlx5-updates-2023-06-16' of git://..
git tree: net-next
final oops: https://syzkaller.appspot.com/x/report.txt?x=16a7cbcf280000
console output: https://syzkaller.appspot.com/x/log.txt?x=12a7cbcf280000

kernel config: https://syzkaller.appspot.com/x/.config?x=a4a7d74e6a7c3211
dashboard link: https://syzkaller.appspot.com/bug?extid=88f4b1e6cf88da11f5cd

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1152c4ff280000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1307cbcf280000

Reported-by: syzbot+88f4b1...@syzkaller.appspotmail.com
Fixes: c662b043cdca ("crypto: af_alg/hash: Support MSG_SPLICE_PAGES")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

[David Howells]

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git main

commit c2996e733d4f2d93bdc0fed74022da082b2e6784
Author: David Howells <dhow...@redhat.com>
Date: Wed Jun 14 13:33:04 2023 +0100

crypto: af_alg/hash: Fix recvmsg() after sendmsg(MSG_MORE)

If an AF_ALG socket bound to a hashing algorithm is sent a zero-length
message with MSG_MORE set and then recvmsg() is called without first
sending another message without MSG_MORE set to end the operation, an oops
will occur because the crypto context and result doesn't now get set up in
advance because hash_sendmsg() now defers that as long as possible in the
hope that it can use crypto_ahash_digest() - and then because the message
is zero-length, it the data wrangling loop is skipped.

Fix this by handling zero-length sends at the top of the hash_sendmsg()
function. If we're not continuing the previous sendmsg(), then just ignore
the send (hash_recvmsg() will invent something when called); if we are
continuing, then we finalise the request at this point if MSG_MORE is not
set to get any error here, otherwise the send is of no effect and can be
ignored.

Whilst we're at it, remove the code to create a kvmalloc'd scatterlist if
we get more than ALG_MAX_PAGES - this shouldn't happen.

Fixes: c662b043cdca ("crypto: af_alg/hash: Support MSG_SPLICE_PAGES")

Reported-by: syzbot+13a08c...@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/000000000000b9...@google.com/
Reported-by: syzbot+14234c...@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/000000000000c0...@google.com/
Reported-by: syzbot+4e2e47...@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/000000000000bc...@google.com/
Reported-by: syzbot+472626...@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/000000000000b5...@google.com/
Signed-off-by: David Howells <dhow...@redhat.com>
cc: Herbert Xu <her...@gondor.apana.org.au>
cc: "David S. Miller" <da...@davemloft.net>
cc: Eric Dumazet <edum...@google.com>
cc: Jakub Kicinski <ku...@kernel.org>
cc: Paolo Abeni <pab...@redhat.com>
cc: Jens Axboe <ax...@kernel.dk>
cc: Matthew Wilcox <wi...@infradead.org>
cc: linux-...@vger.kernel.org
cc: net...@vger.kernel.org

diff --git a/crypto/algif_hash.c b/crypto/algif_hash.c
index dfb048cefb60..0ab43e149f0e 100644
--- a/crypto/algif_hash.c
+++ b/crypto/algif_hash.c
@@ -76,13 +76,30 @@ static int hash_sendmsg(struct socket *sock, struct msghdr *msg,

lock_sock(sk);
if (!continuing) {
- if ((msg->msg_flags & MSG_MORE))
- hash_free_result(sk, ctx);
+ /* Discard a previous request that wasn't marked MSG_MORE. */
+ hash_free_result(sk, ctx);
+ if (!msg_data_left(msg))
+ goto done; /* Zero-length; don't start new req */
need_init = true;
+ } else if (!msg_data_left(msg)) {
+ /*
+ * No data - finalise the prev req if MSG_MORE so any error
+ * comes out here.
+ */
+ if (!(msg->msg_flags & MSG_MORE)) {
+ err = hash_alloc_result(sk, ctx);
+ if (err)
+ goto unlock_free;
+ ahash_request_set_crypt(&ctx->req, NULL,
+ ctx->result, 0);
+ err = crypto_wait_req(crypto_ahash_final(&ctx->req),
+ &ctx->wait);
+ if (err)
+ goto unlock_free;
+ }
+ goto done_more;
}

- ctx->more = false;
-
while (msg_data_left(msg)) {
ctx->sgl.sgt.sgl = ctx->sgl.sgl;
ctx->sgl.sgt.nents = 0;
@@ -93,15 +110,6 @@ static int hash_sendmsg(struct socket *sock, struct msghdr *msg,
if (npages == 0)
goto unlock_free;

- if (npages > ARRAY_SIZE(ctx->sgl.sgl)) {
- err = -ENOMEM;
- ctx->sgl.sgt.sgl =
- kvmalloc(array_size(npages,
- sizeof(*ctx->sgl.sgt.sgl)),
- GFP_KERNEL);
- if (!ctx->sgl.sgt.sgl)
- goto unlock_free;
- }
sg_init_table(ctx->sgl.sgl, npages);

ctx->sgl.need_unpin = iov_iter_extract_will_pin(&msg->msg_iter);
@@ -150,7 +158,9 @@ static int hash_sendmsg(struct socket *sock, struct msghdr *msg,
af_alg_free_sg(&ctx->sgl);
}

+done_more:
ctx->more = msg->msg_flags & MSG_MORE;
+done:
err = 0;
unlock:
release_sock(sk);
@@ -158,6 +168,8 @@ static int hash_sendmsg(struct socket *sock, struct msghdr *msg,

unlock_free:
af_alg_free_sg(&ctx->sgl);
+ hash_free_result(sk, ctx);
+ ctx->more = false;
goto unlock;
}

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+88f4b1...@syzkaller.appspotmail.com

Tested on:

commit: 49310624 Merge branch 'ipv6-random-cleanup-for-extensi..
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git main
console output: https://syzkaller.appspot.com/x/log.txt?x=178ba75b280000

kernel config: https://syzkaller.appspot.com/x/.config?x=a4a7d74e6a7c3211
dashboard link: https://syzkaller.appspot.com/bug?extid=88f4b1e6cf88da11f5cd

compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

patch: https://syzkaller.appspot.com/x/patch.diff?x=11352c83280000

Note: testing is done by a robot and is best-effort only.

[David Howells]

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git main

crypto: af_alg/hash: Fix recvmsg() after sendmsg(MSG_MORE)

If an AF_ALG socket bound to a hashing algorithm is sent a zero-length
message with MSG_MORE set and then recvmsg() is called without first
sending another message without MSG_MORE set to end the operation, an oops
will occur because the crypto context and result doesn't now get set up in
advance because hash_sendmsg() now defers that as long as possible in the
hope that it can use crypto_ahash_digest() - and then because the message
is zero-length, it the data wrangling loop is skipped.

Fix this by always making a pass of the loop, even in the case that no data
is provided to the sendmsg().

Fix also extract_iter_to_sg() to handle a zero-length iterator by returning
0 immediately.

Whilst we're at it, remove the code to create a kvmalloc'd scatterlist if
we get more than ALG_MAX_PAGES - this shouldn't happen.

Fixes: c662b043cdca ("crypto: af_alg/hash: Support MSG_SPLICE_PAGES")

Reported-by: syzbot+13a08c...@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/000000000000b9...@google.com/

Signed-off-by: David Howells <dhow...@redhat.com>
cc: Herbert Xu <her...@gondor.apana.org.au>
cc: "David S. Miller" <da...@davemloft.net>
cc: Eric Dumazet <edum...@google.com>
cc: Jakub Kicinski <ku...@kernel.org>
cc: Paolo Abeni <pab...@redhat.com>
cc: Jens Axboe <ax...@kernel.dk>
cc: Matthew Wilcox <wi...@infradead.org>
cc: linux-...@vger.kernel.org
cc: net...@vger.kernel.org

diff --git a/crypto/algif_hash.c b/crypto/algif_hash.c

index dfb048cefb60..1176533a55c9 100644
--- a/crypto/algif_hash.c
+++ b/crypto/algif_hash.c
@@ -83,26 +83,14 @@ static int hash_sendmsg(struct socket *sock, struct msghdr *msg,

ctx->more = false;

- while (msg_data_left(msg)) {

+ do {

ctx->sgl.sgt.sgl = ctx->sgl.sgl;
ctx->sgl.sgt.nents = 0;

ctx->sgl.sgt.orig_nents = 0;

err = -EIO;
npages = iov_iter_npages(&msg->msg_iter, max_pages);
- if (npages == 0)
- goto unlock_free;
-

- if (npages > ARRAY_SIZE(ctx->sgl.sgl)) {
- err = -ENOMEM;
- ctx->sgl.sgt.sgl =
- kvmalloc(array_size(npages,
- sizeof(*ctx->sgl.sgt.sgl)),
- GFP_KERNEL);
- if (!ctx->sgl.sgt.sgl)
- goto unlock_free;
- }

- sg_init_table(ctx->sgl.sgl, npages);
+ sg_init_table(ctx->sgl.sgl, max_t(size_t, npages, 1));

ctx->sgl.need_unpin = iov_iter_extract_will_pin(&msg->msg_iter);

@@ -111,7 +99,8 @@ static int hash_sendmsg(struct socket *sock, struct msghdr *msg,
if (err < 0)
goto unlock_free;
len = err;
- sg_mark_end(ctx->sgl.sgt.sgl + ctx->sgl.sgt.nents - 1);
+ if (len > 0)
+ sg_mark_end(ctx->sgl.sgt.sgl + ctx->sgl.sgt.nents - 1);

if (!msg_data_left(msg)) {
err = hash_alloc_result(sk, ctx);
@@ -148,7 +137,7 @@ static int hash_sendmsg(struct socket *sock, struct msghdr *msg,

copied += len;
af_alg_free_sg(&ctx->sgl);
- }
+ } while (msg_data_left(msg));

ctx->more = msg->msg_flags & MSG_MORE;

err = 0;
diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index e97d7060329e..77a7b18ee751 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -1340,7 +1340,7 @@ ssize_t extract_iter_to_sg(struct iov_iter *iter, size_t maxsize,
struct sg_table *sgtable, unsigned int sg_max,
iov_iter_extraction_t extraction_flags)
{
- if (maxsize == 0)
+ if (!maxsize || !iter->count)
return 0;

switch (iov_iter_type(iter)) {

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+88f4b1...@syzkaller.appspotmail.com

Tested on:

commit: 49310624 Merge branch 'ipv6-random-cleanup-for-extensi..
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git main

console output: https://syzkaller.appspot.com/x/log.txt?x=141473e3280000

kernel config: https://syzkaller.appspot.com/x/.config?x=a4a7d74e6a7c3211
dashboard link: https://syzkaller.appspot.com/bug?extid=88f4b1e6cf88da11f5cd
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

patch: https://syzkaller.appspot.com/x/patch.diff?x=13365e5b280000

[syzbot]

syzbot suspects this issue was fixed by commit:

commit 1dbcf770cc2d15baf8a1e8174d6fd014a68b45ca
Author: Jiadong Zhu <Jiado...@amd.com>
Date: Wed May 24 03:42:19 2023 +0000

drm/amdgpu: Reset CP_VMID_PREEMPT after trailing fence signaled

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1622cafaa80000
start commit: 9a94d764e9bc Merge tag 'mlx5-updates-2023-06-16' of git://..
git tree: net-next

kernel config: https://syzkaller.appspot.com/x/.config?x=a4a7d74e6a7c3211
dashboard link: https://syzkaller.appspot.com/bug?extid=88f4b1e6cf88da11f5cd

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1152c4ff280000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1307cbcf280000

If the result looks correct, please mark the issue as fixed by replying with:

#syz fix: drm/amdgpu: Reset CP_VMID_PREEMPT after trailing fence signaled

[Aleksandr Nogikh]

On Wed, Jul 19, 2023 at 7:42 PM syzbot
<syzbot+88f4b1...@syzkaller.appspotmail.com> wrote:
>
> syzbot suspects this issue was fixed by commit:
>
> commit 1dbcf770cc2d15baf8a1e8174d6fd014a68b45ca
> Author: Jiadong Zhu <Jiado...@amd.com>
> Date: Wed May 24 03:42:19 2023 +0000
>
> drm/amdgpu: Reset CP_VMID_PREEMPT after trailing fence signaled
>
> bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1622cafaa80000
> start commit: 9a94d764e9bc Merge tag 'mlx5-updates-2023-06-16' of git://..
> git tree: net-next
> kernel config: https://syzkaller.appspot.com/x/.config?x=a4a7d74e6a7c3211
> dashboard link: https://syzkaller.appspot.com/bug?extid=88f4b1e6cf88da11f5cd
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1152c4ff280000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1307cbcf280000
>
> If the result looks correct, please mark the issue as fixed by replying with:

No, that's unrelated.

[David Howells]

#syz fix: crypto: af_alg/hash: Fix recvmsg() after sendmsg(MSG_MORE)