Cc: Naoya Horiguchi <[email protected]>
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 <[email protected]>
Cc: <[email protected]>
Signed-off-by: Li Zefan <[email protected]>
---
Previously it would return -ENODEV, but seems -EINVAL is more appropriate.
---
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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