| Message ID | 20240517091626.32772-1-kuniyu@amazon.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 3ebc46ca8675de6378e3f8f40768e180bb8afa66 |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [v1,net] tcp: Fix shift-out-of-bounds in dctcp_update_alpha(). | expand |
On Fri, May 17, 2024 at 06:16:26PM +0900, Kuniyuki Iwashima wrote: > In dctcp_update_alpha(), we use a module parameter dctcp_shift_g > as follows: > > alpha -= min_not_zero(alpha, alpha >> dctcp_shift_g); > ... > delivered_ce <<= (10 - dctcp_shift_g); > > It seems syzkaller started fuzzing module parameters and triggered > shift-out-of-bounds [0] by setting 100 to dctcp_shift_g: > > memcpy((void*)0x20000080, > "/sys/module/tcp_dctcp/parameters/dctcp_shift_g\000", 47); > res = syscall(__NR_openat, /*fd=*/0xffffffffffffff9cul, /*file=*/0x20000080ul, > /*flags=*/2ul, /*mode=*/0ul); > memcpy((void*)0x20000000, "100\000", 4); > syscall(__NR_write, /*fd=*/r[0], /*val=*/0x20000000ul, /*len=*/4ul); > > Let's limit the max value of dctcp_shift_g by param_set_uint_minmax(). > > With this patch: > > # echo 10 > /sys/module/tcp_dctcp/parameters/dctcp_shift_g > # cat /sys/module/tcp_dctcp/parameters/dctcp_shift_g > 10 > # echo 11 > /sys/module/tcp_dctcp/parameters/dctcp_shift_g > -bash: echo: write error: Invalid argument > > [0]: > UBSAN: shift-out-of-bounds in net/ipv4/tcp_dctcp.c:143:12 > shift exponent 100 is too large for 32-bit type 'u32' (aka 'unsigned int') > CPU: 0 PID: 8083 Comm: syz-executor345 Not tainted 6.9.0-05151-g1b294a1f3561 #2 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS > 1.13.0-1ubuntu1.1 04/01/2014 > Call Trace: > <TASK> > __dump_stack lib/dump_stack.c:88 [inline] > dump_stack_lvl+0x201/0x300 lib/dump_stack.c:114 > ubsan_epilogue lib/ubsan.c:231 [inline] > __ubsan_handle_shift_out_of_bounds+0x346/0x3a0 lib/ubsan.c:468 > dctcp_update_alpha+0x540/0x570 net/ipv4/tcp_dctcp.c:143 > tcp_in_ack_event net/ipv4/tcp_input.c:3802 [inline] > tcp_ack+0x17b1/0x3bc0 net/ipv4/tcp_input.c:3948 > tcp_rcv_state_process+0x57a/0x2290 net/ipv4/tcp_input.c:6711 > tcp_v4_do_rcv+0x764/0xc40 net/ipv4/tcp_ipv4.c:1937 > sk_backlog_rcv include/net/sock.h:1106 [inline] > __release_sock+0x20f/0x350 net/core/sock.c:2983 > release_sock+0x61/0x1f0 net/core/sock.c:3549 > mptcp_subflow_shutdown+0x3d0/0x620 net/mptcp/protocol.c:2907 > mptcp_check_send_data_fin+0x225/0x410 net/mptcp/protocol.c:2976 > __mptcp_close+0x238/0xad0 net/mptcp/protocol.c:3072 > mptcp_close+0x2a/0x1a0 net/mptcp/protocol.c:3127 > inet_release+0x190/0x1f0 net/ipv4/af_inet.c:437 > __sock_release net/socket.c:659 [inline] > sock_close+0xc0/0x240 net/socket.c:1421 > __fput+0x41b/0x890 fs/file_table.c:422 > task_work_run+0x23b/0x300 kernel/task_work.c:180 > exit_task_work include/linux/task_work.h:38 [inline] > do_exit+0x9c8/0x2540 kernel/exit.c:878 > do_group_exit+0x201/0x2b0 kernel/exit.c:1027 > __do_sys_exit_group kernel/exit.c:1038 [inline] > __se_sys_exit_group kernel/exit.c:1036 [inline] > __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1036 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0xe4/0x240 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x67/0x6f > RIP: 0033:0x7f6c2b5005b6 > Code: Unable to access opcode bytes at 0x7f6c2b50058c. > RSP: 002b:00007ffe883eb948 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 > RAX: ffffffffffffffda RBX: 00007f6c2b5862f0 RCX: 00007f6c2b5005b6 > RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 > RBP: 0000000000000001 R08: 00000000000000e7 R09: ffffffffffffffc0 > R10: 0000000000000006 R11: 0000000000000246 R12: 00007f6c2b5862f0 > R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000001 > </TASK> > > Reported-by: syzkaller <syzkaller@googlegroups.com> > Reported-by: Yue Sun <samsun1006219@gmail.com> > Reported-by: xingwei lee <xrivendell7@gmail.com> > Closes: https://lore.kernel.org/netdev/CAEkJfYNJM=cw-8x7_Vmj1J6uYVCWMbbvD=EFmDPVBGpTsqOxEA@mail.gmail.com/ > Fixes: e3118e8359bb ("net: tcp: add DCTCP congestion control algorithm") > Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Reviewed-by: Simon Horman <horms@kernel.org>
Hello: This patch was applied to netdev/net.git (main) by Paolo Abeni <pabeni@redhat.com>: On Fri, 17 May 2024 18:16:26 +0900 you wrote: > In dctcp_update_alpha(), we use a module parameter dctcp_shift_g > as follows: > > alpha -= min_not_zero(alpha, alpha >> dctcp_shift_g); > ... > delivered_ce <<= (10 - dctcp_shift_g); > > [...] Here is the summary with links: - [v1,net] tcp: Fix shift-out-of-bounds in dctcp_update_alpha(). https://git.kernel.org/netdev/net/c/3ebc46ca8675 You are awesome, thank you!
diff --git a/net/ipv4/tcp_dctcp.c b/net/ipv4/tcp_dctcp.c index 6b712a33d49f..8a45a4aea933 100644 --- a/net/ipv4/tcp_dctcp.c +++ b/net/ipv4/tcp_dctcp.c @@ -58,7 +58,18 @@ struct dctcp { }; static unsigned int dctcp_shift_g __read_mostly = 4; /* g = 1/2^4 */ -module_param(dctcp_shift_g, uint, 0644); + +static int dctcp_shift_g_set(const char *val, const struct kernel_param *kp) +{ + return param_set_uint_minmax(val, kp, 0, 10); +} + +static const struct kernel_param_ops dctcp_shift_g_ops = { + .set = dctcp_shift_g_set, + .get = param_get_uint, +}; + +module_param_cb(dctcp_shift_g, &dctcp_shift_g_ops, &dctcp_shift_g, 0644); MODULE_PARM_DESC(dctcp_shift_g, "parameter g for updating dctcp_alpha"); static unsigned int dctcp_alpha_on_init __read_mostly = DCTCP_MAX_ALPHA;
In dctcp_update_alpha(), we use a module parameter dctcp_shift_g as follows: alpha -= min_not_zero(alpha, alpha >> dctcp_shift_g); ... delivered_ce <<= (10 - dctcp_shift_g); It seems syzkaller started fuzzing module parameters and triggered shift-out-of-bounds [0] by setting 100 to dctcp_shift_g: memcpy((void*)0x20000080, "/sys/module/tcp_dctcp/parameters/dctcp_shift_g\000", 47); res = syscall(__NR_openat, /*fd=*/0xffffffffffffff9cul, /*file=*/0x20000080ul, /*flags=*/2ul, /*mode=*/0ul); memcpy((void*)0x20000000, "100\000", 4); syscall(__NR_write, /*fd=*/r[0], /*val=*/0x20000000ul, /*len=*/4ul); Let's limit the max value of dctcp_shift_g by param_set_uint_minmax(). With this patch: # echo 10 > /sys/module/tcp_dctcp/parameters/dctcp_shift_g # cat /sys/module/tcp_dctcp/parameters/dctcp_shift_g 10 # echo 11 > /sys/module/tcp_dctcp/parameters/dctcp_shift_g -bash: echo: write error: Invalid argument [0]: UBSAN: shift-out-of-bounds in net/ipv4/tcp_dctcp.c:143:12 shift exponent 100 is too large for 32-bit type 'u32' (aka 'unsigned int') CPU: 0 PID: 8083 Comm: syz-executor345 Not tainted 6.9.0-05151-g1b294a1f3561 #2 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x201/0x300 lib/dump_stack.c:114 ubsan_epilogue lib/ubsan.c:231 [inline] __ubsan_handle_shift_out_of_bounds+0x346/0x3a0 lib/ubsan.c:468 dctcp_update_alpha+0x540/0x570 net/ipv4/tcp_dctcp.c:143 tcp_in_ack_event net/ipv4/tcp_input.c:3802 [inline] tcp_ack+0x17b1/0x3bc0 net/ipv4/tcp_input.c:3948 tcp_rcv_state_process+0x57a/0x2290 net/ipv4/tcp_input.c:6711 tcp_v4_do_rcv+0x764/0xc40 net/ipv4/tcp_ipv4.c:1937 sk_backlog_rcv include/net/sock.h:1106 [inline] __release_sock+0x20f/0x350 net/core/sock.c:2983 release_sock+0x61/0x1f0 net/core/sock.c:3549 mptcp_subflow_shutdown+0x3d0/0x620 net/mptcp/protocol.c:2907 mptcp_check_send_data_fin+0x225/0x410 net/mptcp/protocol.c:2976 __mptcp_close+0x238/0xad0 net/mptcp/protocol.c:3072 mptcp_close+0x2a/0x1a0 net/mptcp/protocol.c:3127 inet_release+0x190/0x1f0 net/ipv4/af_inet.c:437 __sock_release net/socket.c:659 [inline] sock_close+0xc0/0x240 net/socket.c:1421 __fput+0x41b/0x890 fs/file_table.c:422 task_work_run+0x23b/0x300 kernel/task_work.c:180 exit_task_work include/linux/task_work.h:38 [inline] do_exit+0x9c8/0x2540 kernel/exit.c:878 do_group_exit+0x201/0x2b0 kernel/exit.c:1027 __do_sys_exit_group kernel/exit.c:1038 [inline] __se_sys_exit_group kernel/exit.c:1036 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1036 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xe4/0x240 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x67/0x6f RIP: 0033:0x7f6c2b5005b6 Code: Unable to access opcode bytes at 0x7f6c2b50058c. RSP: 002b:00007ffe883eb948 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 00007f6c2b5862f0 RCX: 00007f6c2b5005b6 RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 RBP: 0000000000000001 R08: 00000000000000e7 R09: ffffffffffffffc0 R10: 0000000000000006 R11: 0000000000000246 R12: 00007f6c2b5862f0 R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000001 </TASK> Reported-by: syzkaller <syzkaller@googlegroups.com> Reported-by: Yue Sun <samsun1006219@gmail.com> Reported-by: xingwei lee <xrivendell7@gmail.com> Closes: https://lore.kernel.org/netdev/CAEkJfYNJM=cw-8x7_Vmj1J6uYVCWMbbvD=EFmDPVBGpTsqOxEA@mail.gmail.com/ Fixes: e3118e8359bb ("net: tcp: add DCTCP congestion control algorithm") Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> --- net/ipv4/tcp_dctcp.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-)