Re: Kernel panic building polyml

[John David Anglin <dave.anglin@bell.net>]

[-- Attachment #1: Type: text/plain, Size: 2379 bytes --]

On 2017-08-19, at 8:56 AM, John David Anglin wrote:

> mx3210 login: systemd-logind[4461]: New seat seat0.
> systemd-logind[4461]: Failed to start user service, ignoring: Unknown unit: user@0.service
> systemd-logind[4461]: Failed to start user service, ignoring: Unknown unit: user@110.service
> Backtrace:
> [<00000000402f316c>] compat_get_fd_set+0x5c/0x78
> [<00000000402f3cac>] compat_core_sys_select+0x1cc/0x300
> [<00000000402f52dc>] compat_SyS_select+0x144/0x1a0
> [<0000000040155fe4>] syscall_exit+0x0/0x14
> 
> 
> Kernel Fault: Code=26 (Data memory access rights trap) regs=00000002234b84e0 (Addr=0000000000000000)
> CPU: 1 PID: 21167 Comm: polyimport Not tainted 4.13.0-rc5+ #1
> task: 0000000223d74b50 task.stack: 00000002234b8000
> 
> YZrvWESTHLNXBCVMcbcbcbcbOGFRQPDI
> PSW: 00001000000001101111111100001111 Not tainted
> r00-03 000000ff0806ff0f 00000002234b8420 00000000402f316c 00000002234b84a0
> r04-07 000000004071c960 00000002234b82b8 00000002234b8218 0000000000000100
> r08-11 0000000000000004 0000000000000100 00000000f3780588 0000000000000000
> r12-15 0000000000000000 00000002234b8148 0000000000000000 00000002234b8218
> r16-19 0000000000000000 000000000002f03c 000000000002f030 0000000000000000
> r20-23 0000000000000100 0000000000000000 00000002234b8148 0000000000000000
> r24-27 0000000000000100 0000000000000000 0000000000000000 000000004071c960
> r28-31 0000000000000000 00000002234b8470 00000002234b84e0 0000000000000000
> sr00-03 0000000003f15000 0000000003f15000 0000000003f15000 0000000003f15000
> sr04-07 0000000000000000 0000000000000000 0000000000000000 0000000000000000
> 
> IASQ: 0000000000000000 0000000000000000 IAOQ: 00000000406a4718 00000000406a471c
> IIR: 0ff312c0 ISR: 0000000000000000 IOR: 0000000000000000
> CPU: 1 CR30: 00000002234b8000 CR31: b33e06ff0008e07f
> ORIG_R28: 0000000000000040
> IAOQ[0]: memset+0x68/0xd8
> IAOQ[1]: memset+0x6c/0xd8
> RP(r2): compat_get_fd_set+0x5c/0x78
> Backtrace:
> [<00000000402f316c>] compat_get_fd_set+0x5c/0x78
> [<00000000402f3cac>] compat_core_sys_select+0x1cc/0x300
> [<00000000402f52dc>] compat_SyS_select+0x144/0x1a0
> [<0000000040155fe4>] syscall_exit+0x0/0x14
> 
> Kernel panic - not syncing: Kernel Fault
> ---[ end Kernel panic - not syncing: Kernel Fault


The attached patch is probably not the real fix but it should prevent the panic.



[-- Attachment #2: select.d.txt --]
[-- Type: text/plain, Size: 456 bytes --]

diff --git a/fs/select.c b/fs/select.c
index d6c652a31e99..8790c0a0bd3c 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -1181,6 +1181,8 @@ int compat_get_fd_set(unsigned long nr, compat_ulong_t __user *ufdset,
 		if (odd && __get_user(*fdset, ufdset))
 			return -EFAULT;
 	} else {
+		if (!fdset)
+			return -EFAULT;
 		/* Tricky, must clear full unsigned long in the
 		 * kernel fdset at the end, this makes sure that
 		 * actually happens.

[-- Attachment #3: Type: text/plain, Size: 116 bytes --]



--
John David Anglin	dave.anglin@bell.net

PS: the above crash is what broke the dsa-puppet git archive on mx3210.