Hi Al, On Fri, Jul 24, 2020 at 02:25:46AM +0100, Al Viro wrote: > From: Al Viro <viro@xxxxxxxxxxxxxxxxxx> > > ... and get rid of the pointless fallback in the wrappers. On error it used > to zero the unwritten area and calculate the csum of the entire thing. Not > wanting to do it in assembler part had been very reasonable; doing that in > the first place, OTOH... In case of an error the caller discards the data > we'd copied, along with whatever checksum it might've had. This patch is causing crashes in WireGuard's CI over at https://www.wireguard.com/build-status/ . Apparently sending a simple network packet winds up triggering refcount_t's warn-on-saturate code. I don't know if the new assembly failed to reset some flag or if something else is up. I can start digging into it if you want, but I thought I should let you know first about the issue. The splat follows below. Thanks, Jason $ ping -c 10 -f -W 1 192.168.241.1 PING 192.168.241.1 (192.168.241.1) 56(84) bytes of data. [ 1.432922] ------------[ cut here ]------------ [ 1.433069] refcount_t: saturated; leaking memory. [ 1.433344] WARNING: CPU: 3 PID: 90 at refcount_warn_saturate+0x100/0x1bc [ 1.433646] CPU: 3 PID: 90 Comm: ping Not tainted 5.9.0+ #3 [ 1.433797] NIP: c01a6fa0 LR: c01a6fa0 CTR: c01ccbec [ 1.433964] REGS: cfacfb80 TRAP: 0700 Not tainted (5.9.0+) [ 1.434102] MSR: 00029000 <CE,EE,ME> CR: 28022404 XER: 00000000 [ 1.434345] [ 1.434345] GPR00: c01a6fa0 cfacfc38 cf8eeae0 00000026 3fffefff cfacfa90 cfacfaa0 00021000 [ 1.434345] GPR08: 0f4a1000 00000000 c08b4674 c0918704 42022404 00000000 cfa34180 00000000 [ 1.434345] GPR16: 00000000 cf8ef004 00000000 00000000 00000040 00000000 00000000 cfbac230 [ 1.434345] GPR24: cfacfce8 c02a802c 00000000 cfa34180 cfacfc58 c02aa53c 55c0a4ff 00000000 [ 1.435471] NIP [c01a6fa0] refcount_warn_saturate+0x100/0x1bc [ 1.435615] LR [c01a6fa0] refcount_warn_saturate+0x100/0x1bc [ 1.435825] Call Trace: [ 1.435922] [cfacfc38] [c01a6fa0] refcount_warn_saturate+0x100/0x1bc (unreliable) [ 1.436149] [cfacfc48] [c02a7f14] __ip_append_data.isra.0+0x8a8/0xde0 [ 1.436302] [cfacfce8] [c02a84e0] ip_append_data.part.0+0x94/0xf0 [ 1.436438] [cfacfd18] [c02dffe0] raw_sendmsg+0x298/0xa84 [ 1.436544] [cfacfe48] [c020b9ec] __sys_sendto+0xdc/0x13c [ 1.436641] [cfacff38] [c000f1dc] ret_from_syscall+0x0/0x38 [ 1.436824] --- interrupt: c01 at 0xb7e44f00 [ 1.436824] LR = 0xb7e21ba0 [ 1.437038] Instruction dump: [ 1.437239] 3d20c092 39291bc1 89490001 2c0a0000 4082ff64 3c60c040 7c0802a6 39400001 [ 1.437439] 38633b74 90010014 99490001 4be9b6e1 <0fe00000> 80010014 7c0803a6 4bffff38 [ 1.437753] ---[ end trace aaa4b4788958d0a6 ]--- [ 1.440214] ------------[ cut here ]------------ [ 1.440301] refcount_t: underflow; use-after-free. [ 1.440397] WARNING: CPU: 3 PID: 90 at refcount_warn_saturate+0x1ac/0x1bc [ 1.440587] CPU: 3 PID: 90 Comm: ping Tainted: G W 5.9.0+ #3 [ 1.440741] NIP: c01a704c LR: c01a704c CTR: c01ccbec [ 1.440857] REGS: cfacfaa0 TRAP: 0700 Tainted: G W (5.9.0+) [ 1.441016] MSR: 00029000 <CE,EE,ME> CR: 48022404 XER: 00000000 [ 1.441176] [ 1.441176] GPR00: c01a704c cfacfb58 cf8eeae0 00000026 3fffefff cfacf9b0 cfacf9c0 00021000 [ 1.441176] GPR08: 0f4a1000 00000400 c08b4674 c0918704 42022404 00000000 10020464 00000003 [ 1.441176] GPR16: 7ff00000 10020000 00000080 cfb27000 cfb2704c c0930000 cfacfc54 c092d260 [ 1.441176] GPR24: 0000058c cfa82120 cfa8212c cfa8212c 00000000 cfa82000 cfacfd44 cfacfc58 [ 1.441995] NIP [c01a704c] refcount_warn_saturate+0x1ac/0x1bc [ 1.442125] LR [c01a704c] refcount_warn_saturate+0x1ac/0x1bc [ 1.442252] Call Trace: [ 1.442320] [cfacfb58] [c01a704c] refcount_warn_saturate+0x1ac/0x1bc (unreliable) [ 1.442726] [cfacfb68] [c020e7dc] sock_wfree+0x130/0x134 [ 1.442877] [cfacfb78] [c01f1388] wg_packet_send_staged_packets+0x234/0x6b4 [ 1.443061] [cfacfbb8] [c01eecf8] wg_xmit+0x2a0/0x46c [ 1.443204] [cfacfbf8] [c0232134] dev_hard_start_xmit+0x190/0x1c0 [ 1.443369] [cfacfc38] [c0232f2c] __dev_queue_xmit+0x4d0/0x844 [ 1.443527] [cfacfc88] [c02a7134] ip_finish_output2+0x180/0x6b8 [ 1.443686] [cfacfcb8] [c02aa3e8] ip_output+0xf0/0x1c0 [ 1.443829] [cfacfd08] [c02ab14c] ip_send_skb+0x24/0xe8 [ 1.443975] [cfacfd18] [c02e04bc] raw_sendmsg+0x774/0xa84 [ 1.444124] [cfacfe48] [c020b9ec] __sys_sendto+0xdc/0x13c [ 1.444274] [cfacff38] [c000f1dc] ret_from_syscall+0x0/0x38 [ 1.444437] --- interrupt: c01 at 0xb7e44f00 [ 1.444437] LR = 0xb7e21ba0 [ 1.444644] Instruction dump: [ 1.444736] 4be9b661 0fe00000 80010014 7c0803a6 4bfffeb8 3c60c040 7c0802a6 39400001 [ 1.444989] 38633bd8 90010014 99490003 4be9b635 <0fe00000> 80010014 7c0803a6 4bfffe8c [ 1.445252] ---[ end trace aaa4b4788958d0a7 ]--- [ 1.445583] BUG: Unable to handle kernel instruction fetch (NULL pointer?) [ 1.445767] Faulting instruction address: 0x00000000 [ 1.446051] Oops: Kernel access of bad area, sig: 11 [#1] [ 1.446210] BE PAGE_SIZE=4K PREEMPT SMP NR_CPUS=4 QEMU e500 [ 1.446379] CPU: 3 PID: 90 Comm: ping Tainted: G W 5.9.0+ #3 [ 1.446678] NIP: 00000000 LR: c020e758 CTR: 00000000 [ 1.446812] REGS: cfacfab0 TRAP: 0400 Tainted: G W (5.9.0+) [ 1.446989] MSR: 00029000 <CE,EE,ME> CR: 48022404 XER: 00000000 [ 1.447183] [ 1.447183] GPR00: c020e7dc cfacfb68 cf8eeae0 cfacfc58 3fffefff cfacf9b0 cfacf9c0 00021000 [ 1.447183] GPR08: 0f4a1000 00000000 c08b4674 c0918704 42022404 00000000 10020464 00000003 [ 1.447183] GPR16: 7ff00000 10020000 00000080 cfb27000 cfb2704c c0930000 cfacfc54 c092d260 [ 1.447183] GPR24: 0000058c cfa82120 cfa8212c cfa8212c 00000000 cfa82000 cfacfd44 cfacfc58 [ 1.448144] NIP [00000000] 0x0 [ 1.448236] LR [c020e758] sock_wfree+0xac/0x134 [ 1.448351] Call Trace: [ 1.448425] [cfacfb68] [c020e7dc] sock_wfree+0x130/0x134 (unreliable) [ 1.448603] [cfacfb78] [c01f1388] wg_packet_send_staged_packets+0x234/0x6b4 [ 1.448820] [cfacfbb8] [c01eecf8] wg_xmit+0x2a0/0x46c [ 1.448964] [cfacfbf8] [c0232134] dev_hard_start_xmit+0x190/0x1c0 [ 1.449139] [cfacfc38] [c0232f2c] __dev_queue_xmit+0x4d0/0x844 [ 1.449304] [cfacfc88] [c02a7134] ip_finish_output2+0x180/0x6b8 [ 1.449475] [cfacfcb8] [c02aa3e8] ip_output+0xf0/0x1c0 [ 1.449628] [cfacfd08] [c02ab14c] ip_send_skb+0x24/0xe8 [ 1.449815] [cfacfd18] [c02e04bc] raw_sendmsg+0x774/0xa84 [ 1.449983] [cfacfe48] [c020b9ec] __sys_sendto+0xdc/0x13c [ 1.450150] [cfacff38] [c000f1dc] ret_from_syscall+0x0/0x38 [ 1.450320] --- interrupt: c01 at 0xb7e44f00 [ 1.450320] LR = 0xb7e21ba0 [ 1.450794] Instruction dump: [ 1.450963] XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX [ 1.451209] XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX [ 1.451637] ---[ end trace aaa4b4788958d0a8 ]--- [ 1.451785] [ 2.555288] Kernel panic - not syncing: Aiee, killing interrupt handler!
