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SubjectRe: SHM oops in newseg()
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On Thu, 2013-05-09 at 15:08 +0800, Li Zefan wrote:
> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
>
> On 2013/5/9 12:35, Dave Jones wrote:
> > Just saw this on v3.9-11789-ge0fd9af while fuzz-testing.
> >
> > [ 163.917836] BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
> > [ 163.918984] IP: [<ffffffff812c48ed>] newseg+0x10d/0x390
>
> The patch below should fix it.
>
> ===========================
>
> [PATCH] shm: fix null pointer deref when userspace specifies invalid hugepage size
>
> Dave reported an oops triggered by trinity:
>
> [ 163.917836] BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
> [ 163.918984] IP: [<ffffffff812c48ed>] newseg+0x10d/0x390
> [ 163.919705] PGD cf8c1067 PUD cf8c2067 PMD 0
> [ 163.920326] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
> [ 163.929949] CPU: 2 PID: 7636 Comm: trinity-child2 Not tainted 3.9.0+#67
> ...
> [ 163.953629] Call Trace:
> [ 163.957706] [<ffffffff812be322>] ipcget+0x182/0x380
> [ 163.962123] [<ffffffff810b99a5>] ?trace_hardirqs_on_caller+0x115/0x1e0
> [ 163.966752] [<ffffffff812c559a>] SyS_shmget+0x5a/0x60
> [ 163.971163] [<ffffffff812c47e0>] ? shm_close+0x140/0x140
> [ 163.975590] [<ffffffff812c3e60>] ? shm_release+0x50/0x50
> [ 163.979991] [<ffffffff812c3df0>] ? shm_get_unmapped_area+0x20/0x20
> [ 163.984499] [<ffffffff816caa14>] tracesys+0xdd/0xe2
>
> This bug was introduced by commit af73e4d9506d3b797509f3c030e7dcd554f7d9c4
> ("hugetlbfs: fix mmap failure in unaligned size request").
>
> Reported-by: Dave Jones <davej@redhat.com>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Li Zefan <lizfan@huawei.com>
> ---
>
> Previously it would return -ENODEV, but seems -EINVAL is more appropriate.

Should the user in fs/hugetlbfs/inode.c be updated as well?
get_hstate_idx() is just returning -1 and it's only caller,
hugetlb_file_setup(), returns -ENODEV.

Thanks,
Davidlohr



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