Re: SHM oops in newseg()
From: Naoya Horiguchi
Date: Thu May 09 2013 - 10:42:46 EST
On Thu, May 09, 2013 at 03:08:15PM +0800, Li Zefan wrote:
> Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
>
> 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@xxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Li Zefan <lizfan@xxxxxxxxxx>
Thank you.
Reviewed-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
> ---
>
> Previously it would return -ENODEV, but seems -EINVAL is more appropriate.
Agreed.
Thanks,
Naoya
> ---
> ipc/shm.c | 8 +++++++-
> mm/mmap.c | 8 ++++++--
> 2 files changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/ipc/shm.c b/ipc/shm.c
> index 34af1fe..7e199fa 100644
> --- a/ipc/shm.c
> +++ b/ipc/shm.c
> @@ -493,7 +493,13 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
> if (shmflg & SHM_HUGETLB) {
> struct hstate *hs = hstate_sizelog((shmflg >> SHM_HUGE_SHIFT)
> & SHM_HUGE_MASK);
> - size_t hugesize = ALIGN(size, huge_page_size(hs));
> + size_t hugesize;
> +
> + if (!hs) {
> + error = -EINVAL;
> + goto no_file;
> + }
> + hugesize = ALIGN(size, huge_page_size(hs));
>
> /* hugetlb_file_setup applies strict accounting */
> if (shmflg & SHM_NORESERVE)
> diff --git a/mm/mmap.c b/mm/mmap.c
> index 1ae21d6..f681e18 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -1367,9 +1367,13 @@ SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
> len = ALIGN(len, huge_page_size(hstate_file(file)));
> } else if (flags & MAP_HUGETLB) {
> struct user_struct *user = NULL;
> + struct hstate *hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) &
> + SHM_HUGE_MASK);
>
> - len = ALIGN(len, huge_page_size(hstate_sizelog(
> - (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK)));
> + if (!hs)
> + return -EINVAL;
> +
> + len = ALIGN(len, huge_page_size(hs));
> /*
> * VM_NORESERVE is used because the reservations will be
> * taken when vm_ops->mmap() is called
> --
> 1.8.0.2
>
>
>
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