* [syzbot] [rds?] general protection fault in rds_tcp_accept_one
@ 2026-02-09 15:41 syzbot
2026-02-10 2:15 ` Forwarded: " syzbot
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: syzbot @ 2026-02-09 15:41 UTC (permalink / raw)
To: allison.henderson, davem, edumazet, horms, kuba, linux-kernel,
linux-rdma, netdev, pabeni, rds-devel, syzkaller-bugs
Hello,
syzbot found the following issue on:
HEAD commit: 9845cf73f7db Add linux-next specific files for 20260205
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=10ec4a5a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=ac78ce3b6729749e
dashboard link: https://syzkaller.appspot.com/bug?extid=96046021045ffe6d7709
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=122acb22580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=149fc7fa580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/9f30334a2431/disk-9845cf73.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0d58741a15a6/vmlinux-9845cf73.xz
kernel image: https://storage.googleapis.com/syzbot-assets/62204da1452c/bzImage-9845cf73.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+96046021045ffe6d7709@syzkaller.appspotmail.com
netdevsim netdevsim1 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]
CPU: 1 UID: 0 PID: 3485 Comm: kworker/u8:8 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: krdsd rds_tcp_accept_worker
RIP: 0010:rds_tcp_accept_one+0xa5b/0xd70 net/rds/tcp_listen.c:319
Code: 00 00 48 83 c3 18 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 63 a9 2f f7 48 8b 1b 48 83 c3 12 49 89 de 49 c1 ee 03 <43> 0f b6 04 2e 84 c0 0f 85 53 02 00 00 44 0f b6 2b bf 08 00 00 00
RSP: 0018:ffffc9000b64f9a0 EFLAGS: 00010202
RAX: 1ffff1100dacb173 RBX: 0000000000000012 RCX: 0000000000000000
RDX: 0000000000000006 RSI: ffffffff8e006fa9 RDI: 00000000ffffffff
RBP: ffffc9000b64fb18 R08: ffffffff903342b7 R09: 1ffffffff2066856
R10: dffffc0000000000 R11: fffffbfff2066857 R12: ffff88803286c000
R13: dffffc0000000000 R14: 0000000000000002 R15: 1ffff920016c9f3c
FS: 0000000000000000(0000) GS:ffff888125115000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f30359456b8 CR3: 00000000320ee000 CR4: 00000000003526f0
Call Trace:
<TASK>
rds_tcp_accept_worker+0x1d/0x70 net/rds/tcp.c:524
process_one_work+0x949/0x1650 kernel/workqueue.c:3279
process_scheduled_works kernel/workqueue.c:3362 [inline]
worker_thread+0xb46/0x1140 kernel/workqueue.c:3443
kthread+0x388/0x470 kernel/kthread.c:467
ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:rds_tcp_accept_one+0xa5b/0xd70 net/rds/tcp_listen.c:319
Code: 00 00 48 83 c3 18 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 63 a9 2f f7 48 8b 1b 48 83 c3 12 49 89 de 49 c1 ee 03 <43> 0f b6 04 2e 84 c0 0f 85 53 02 00 00 44 0f b6 2b bf 08 00 00 00
RSP: 0018:ffffc9000b64f9a0 EFLAGS: 00010202
RAX: 1ffff1100dacb173 RBX: 0000000000000012 RCX: 0000000000000000
RDX: 0000000000000006 RSI: ffffffff8e006fa9 RDI: 00000000ffffffff
RBP: ffffc9000b64fb18 R08: ffffffff903342b7 R09: 1ffffffff2066856
R10: dffffc0000000000 R11: fffffbfff2066857 R12: ffff88803286c000
R13: dffffc0000000000 R14: 0000000000000002 R15: 1ffff920016c9f3c
FS: 0000000000000000(0000) GS:ffff888125115000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f303594da08 CR3: 000000000e74c000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
0: 00 00 add %al,(%rax)
2: 48 83 c3 18 add $0x18,%rbx
6: 48 89 d8 mov %rbx,%rax
9: 48 c1 e8 03 shr $0x3,%rax
d: 42 80 3c 28 00 cmpb $0x0,(%rax,%r13,1)
12: 74 08 je 0x1c
14: 48 89 df mov %rbx,%rdi
17: e8 63 a9 2f f7 call 0xf72fa97f
1c: 48 8b 1b mov (%rbx),%rbx
1f: 48 83 c3 12 add $0x12,%rbx
23: 49 89 de mov %rbx,%r14
26: 49 c1 ee 03 shr $0x3,%r14
* 2a: 43 0f b6 04 2e movzbl (%r14,%r13,1),%eax <-- trapping instruction
2f: 84 c0 test %al,%al
31: 0f 85 53 02 00 00 jne 0x28a
37: 44 0f b6 2b movzbl (%rbx),%r13d
3b: bf 08 00 00 00 mov $0x8,%edi
---
This report is generated by a bot. It may contain errors.
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^ permalink raw reply [flat|nested] 4+ messages in thread* Forwarded: Re: [syzbot] [rds?] general protection fault in rds_tcp_accept_one
2026-02-09 15:41 [syzbot] [rds?] general protection fault in rds_tcp_accept_one syzbot
@ 2026-02-10 2:15 ` syzbot
2026-02-10 7:05 ` syzbot
2026-02-10 7:31 ` syzbot
2 siblings, 0 replies; 4+ messages in thread
From: syzbot @ 2026-02-10 2:15 UTC (permalink / raw)
To: linux-kernel, syzkaller-bugs
For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.
***
Subject: Re: [syzbot] [rds?] general protection fault in rds_tcp_accept_one
Author: allison.henderson@oracle.com
#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git main
commit 86b003db7ed7f474c3f462643c2912ffdeb2f876
Author: Allison Henderson <achender@kernel.org>
Date: Mon Feb 9 18:20:42 2026 -0700
net/rds: Fix NULL pointer dereference in rds_tcp_accept_one
Hold a local reference to new_sock->sk before installing callbacks
in rds_tcp_accept_one. After rds_tcp_set_callbacks() or
rds_tcp_reset_callbacks(), tc->t_sock is set to new_sock which
may race with the shutdown path. A concurrent
rds_tcp_conn_path_shutdown() may call sock_release(), which sets
new_sock->sk = NULL and frees sk.
Subsequent accesses to new_sock->sk->sk_state dereference NULL,
causing the null dereference. So a local sock reference with
sock_hold() before installing callbacks will prevent the race.
Fixes: 826c1004d4ae ("net/rds: rds_tcp_conn_path_shutdown must not discard messages")
Reported-by: syzbot+96046021045ffe6d7709@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=96046021045ffe6d7709
Signed-off-by: Allison Henderson <achender@kernel.org>
diff --git a/net/rds/tcp_listen.c b/net/rds/tcp_listen.c
index 6fb5c928b8fd..cdc86473a1ba 100644
--- a/net/rds/tcp_listen.c
+++ b/net/rds/tcp_listen.c
@@ -177,6 +177,7 @@ int rds_tcp_accept_one(struct rds_tcp_net *rtn)
struct rds_tcp_connection *rs_tcp = NULL;
int conn_state;
struct rds_conn_path *cp;
+ struct sock *sk;
struct in6_addr *my_addr, *peer_addr;
#if !IS_ENABLED(CONFIG_IPV6)
struct in6_addr saddr, daddr;
@@ -298,6 +299,14 @@ int rds_tcp_accept_one(struct rds_tcp_net *rtn)
rds_conn_path_drop(cp, 0);
goto rst_nsk;
}
+ /* Hold a local reference to sk before setting callbacks. Once callbacks
+ * are set, it is possible for a concurrent rds_tcp_conn_path_shutdown
+ * call to release the new_sock->sk and set it to NULL. So we use
+ * a local sk here to avoid racing with callbacks
+ */
+ sk = new_sock->sk;
+ sock_hold(sk);
+
if (rs_tcp->t_sock) {
/* Duelling SYN has been handled in rds_tcp_accept_one() */
rds_tcp_reset_callbacks(new_sock, cp);
@@ -316,13 +325,15 @@ int rds_tcp_accept_one(struct rds_tcp_net *rtn)
* knowing that "rds_tcp_conn_path_shutdown" will
* dequeue pending messages.
*/
- if (new_sock->sk->sk_state == TCP_CLOSE_WAIT ||
- new_sock->sk->sk_state == TCP_LAST_ACK ||
- new_sock->sk->sk_state == TCP_CLOSE)
+ if (READ_ONCE(sk->sk_state) == TCP_CLOSE_WAIT ||
+ READ_ONCE(sk->sk_state) == TCP_LAST_ACK ||
+ READ_ONCE(sk->sk_state) == TCP_CLOSE)
rds_conn_path_drop(cp, 0);
else
queue_delayed_work(cp->cp_wq, &cp->cp_recv_w, 0);
+ sock_put(sk);
+
new_sock = NULL;
ret = 0;
if (conn->c_npaths == 0)
^ permalink raw reply related [flat|nested] 4+ messages in thread* Forwarded: Re: [syzbot] [rds?] general protection fault in rds_tcp_accept_one
2026-02-09 15:41 [syzbot] [rds?] general protection fault in rds_tcp_accept_one syzbot
2026-02-10 2:15 ` Forwarded: " syzbot
@ 2026-02-10 7:05 ` syzbot
2026-02-10 7:31 ` syzbot
2 siblings, 0 replies; 4+ messages in thread
From: syzbot @ 2026-02-10 7:05 UTC (permalink / raw)
To: linux-kernel, syzkaller-bugs
For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.
***
Subject: Re: [syzbot] [rds?] general protection fault in rds_tcp_accept_one
Author: allison.henderson@oracle.com
#syz test: git@github.com:allisonhenderson/rds_work.git rds_tcp_bug_fixes_v14
commit 86b003db7ed7f474c3f462643c2912ffdeb2f876
Author: Allison Henderson <achender@kernel.org>
Date: Mon Feb 9 18:20:42 2026 -0700
net/rds: Fix NULL pointer dereference in rds_tcp_accept_one
Hold a local reference to new_sock->sk before installing callbacks
in rds_tcp_accept_one. After rds_tcp_set_callbacks() or
rds_tcp_reset_callbacks(), tc->t_sock is set to new_sock which
may race with the shutdown path. A concurrent
rds_tcp_conn_path_shutdown() may call sock_release(), which sets
new_sock->sk = NULL and frees sk.
Subsequent accesses to new_sock->sk->sk_state dereference NULL,
causing the null dereference. So a local sock reference with
sock_hold() before installing callbacks will prevent the race.
Fixes: 826c1004d4ae ("net/rds: rds_tcp_conn_path_shutdown must not discard messages")
Reported-by: syzbot+96046021045ffe6d7709@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=96046021045ffe6d7709
Signed-off-by: Allison Henderson <achender@kernel.org>
diff --git a/net/rds/tcp_listen.c b/net/rds/tcp_listen.c
index 6fb5c928b8fd..cdc86473a1ba 100644
--- a/net/rds/tcp_listen.c
+++ b/net/rds/tcp_listen.c
@@ -177,6 +177,7 @@ int rds_tcp_accept_one(struct rds_tcp_net *rtn)
struct rds_tcp_connection *rs_tcp = NULL;
int conn_state;
struct rds_conn_path *cp;
+ struct sock *sk;
struct in6_addr *my_addr, *peer_addr;
#if !IS_ENABLED(CONFIG_IPV6)
struct in6_addr saddr, daddr;
@@ -298,6 +299,14 @@ int rds_tcp_accept_one(struct rds_tcp_net *rtn)
rds_conn_path_drop(cp, 0);
goto rst_nsk;
}
+ /* Hold a local reference to sk before setting callbacks. Once callbacks
+ * are set, it is possible for a concurrent rds_tcp_conn_path_shutdown
+ * call to release the new_sock->sk and set it to NULL. So we use
+ * a local sk here to avoid racing with callbacks
+ */
+ sk = new_sock->sk;
+ sock_hold(sk);
+
if (rs_tcp->t_sock) {
/* Duelling SYN has been handled in rds_tcp_accept_one() */
rds_tcp_reset_callbacks(new_sock, cp);
@@ -316,13 +325,15 @@ int rds_tcp_accept_one(struct rds_tcp_net *rtn)
* knowing that "rds_tcp_conn_path_shutdown" will
* dequeue pending messages.
*/
- if (new_sock->sk->sk_state == TCP_CLOSE_WAIT ||
- new_sock->sk->sk_state == TCP_LAST_ACK ||
- new_sock->sk->sk_state == TCP_CLOSE)
+ if (READ_ONCE(sk->sk_state) == TCP_CLOSE_WAIT ||
+ READ_ONCE(sk->sk_state) == TCP_LAST_ACK ||
+ READ_ONCE(sk->sk_state) == TCP_CLOSE)
rds_conn_path_drop(cp, 0);
else
queue_delayed_work(cp->cp_wq, &cp->cp_recv_w, 0);
+ sock_put(sk);
+
new_sock = NULL;
ret = 0;
if (conn->c_npaths == 0)
^ permalink raw reply related [flat|nested] 4+ messages in thread* Forwarded: Re: [syzbot] [rds?] general protection fault in rds_tcp_accept_one
2026-02-09 15:41 [syzbot] [rds?] general protection fault in rds_tcp_accept_one syzbot
2026-02-10 2:15 ` Forwarded: " syzbot
2026-02-10 7:05 ` syzbot
@ 2026-02-10 7:31 ` syzbot
2 siblings, 0 replies; 4+ messages in thread
From: syzbot @ 2026-02-10 7:31 UTC (permalink / raw)
To: linux-kernel, syzkaller-bugs
For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.
***
Subject: Re: [syzbot] [rds?] general protection fault in rds_tcp_accept_one
Author: allison.henderson@oracle.com
#syz test: https://github.com/allisonhenderson/rds_work.git rds_tcp_bug_fixes_v15
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2026-02-10 7:31 UTC | newest]
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