kernel panic in generic_file_write

[dvyukov]

Got this while running syzkaller on 2b284c49cea87c10f281ed331a939e6698eb43e6:

bash-4.3$ kernel panic at kern/src/vfs.c:1359, from core 1: assertion failed: buf == buf_end
Entering Nanwan's Dungeon on Core 1 (Ints on):
Type 'help' for a list of commands.
ROS(Core 1)> bash-4.3$ bt
Stack Backtrace on Core 1:
#01 [<0xffffffffc2016074>] in mon_backtrace
#02 [<0xffffffffc2017177>] in monitor
#03 [<0xffffffffc200cbfc>] in _panic
#04 [<0xffffffffc205c51c>] in generic_file_write
#05 [<0xffffffffc2053890>] in sys_write
#06 [<0xffffffffc2056919>] in syscall
#07 [<0xffffffffc2056ad4>] in run_local_syscall
#08 [<0xffffffffc20a28aa>] in sysenter_callwrapper

Unfortunately our ability to localize and produce reproducers is limited due to no Go support.

[akaros-notifier]

On 2017-11-01 at 16:41 Dmitry Vyukov notifications@github.com wrote:

Unfortunately our ability to localize and produce reproducers is limited due to no Go support.

Yeah, that makes it a little rough.

Do you have a log of what the syscall arguments were? Even something like the last 100 calls would help.

[akaros-notifier]

On 2017-11-01 at 14:55 Barret Rhoden brho@cs.berkeley.edu wrote:

Do you have a log of what the syscall arguments were? Even something like the last 100 calls would help.

Alternatively, I can run the syzkaller. Is there an easy way to seed it or something so I can have it make the same calls that it did for you? If not, no big deal.

For this particular bug, I might be able to solve it by looking at the code (might be an assumption that breaks for misaligned writes or something), but it'd be nice to have some path to repeating the bug so anyone can try and fix it.

Of course, a working Go 1.9 would be nice too. =)

[akaros-notifier]

Has the Go port been updated since I last updated it to 1.3 many moons ago?

Kevin

On Thu, Nov 2, 2017 at 5:23 PM Barret Rhoden brho@cs.berkeley.edu wrote:

On 2017-11-01 at 14:55 Barret Rhoden brho@cs.berkeley.edu wrote:

Do you have a log of what the syscall arguments were? Even something like the last 100 calls would help.

Alternatively, I can run the syzkaller. Is there an easy way to seed it or something so I can have it make the same calls that it did for you? If not, no big deal.

For this particular bug, I might be able to solve it by looking at the code (might be an assumption that breaks for misaligned writes or something), but it'd be nice to have some path to repeating the bug so anyone can try and fix it.

Of course, a working Go 1.9 would be nice too. =)

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[dvyukov]

No, because you did not accept my pull request :) https://github.com/akaros/go-akaros/pull/1

But seriously, unfortunately that won't help as we need Go 1.9+.

[brho]

Sorry! I didn't see your pull request in the go-akaros repo.