Subject: [Bug 205183] PPC64: Signal delivery fails with SIGSEGV if between about 1KB and 4KB bytes of stack remain

From: [email-masked]
Date: Mon, 18 Nov 2019 04:28:47 +0000

https://bugzilla.kernel.org/show_bug.cgi?id=205183

Daniel Black ([email-masked]) changed:

           What    |Removed                     |Added
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                 CC|                            [email-masked]

--- Comment #1 from Daniel Black ([email-masked]) ---
Tom,

Thanks for the bug report. Appreciate it. Feel free to use the
[email-masked] list.

Reproduced in 5.4.0-rc8

danielgb@talos2:~$ uname -a
Linux talos2 5.4.0-rc8 #5 SMP Mon Nov 18 13:27:11 AEDT 2019 ppc64le ppc64le
ppc64le GNU/Linux
danielgb@talos2:~$ gcc -g -Wall -O stacktest.c
danielgb@talos2:~$ ./a.out 1240000 &
[1] 2944
danielgb@talos2:~$  cat /proc/$(pidof a.out)/maps | grep stack
7fffc62f0000-7fffc6420000 rw-p 00000000 00:00 0                         
[stack]
danielgb@talos2:~$ kill -USR1 %1
danielgb@talos2:~$ signal delivered, stack base 0x7fffc6420000 top
0x7fffc62f1427 (1240025 used)

[1]+  Done                    ./a.out 1240000
danielgb@talos2:~$  ./a.out 1241000 &
[1] 2948
danielgb@talos2:~$ kill -USR1 %1
danielgb@talos2:~$ 
[1]+  Segmentation fault      ./a.out 1241000

[ 6415.077590] a.out[2948]: bad frame in setup_rt_frame: 00007fffe4fb0010 nip
000006a185d909fc lr 000077ecda3c04e8

I'll get someone to look at this soon.

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