From 509dc1bde975d219db0cc55c009c30777e5ce8d4 Mon Sep 17 00:00:00 2001 From: Li Zefan Date: Thu, 9 May 2013 15:08:15 +0800 Subject: [PATCH] shm: fix null pointer deref when userspace specifies invalid hugepage size Dave reported an oops triggered by trinity: BUG: unable to handle kernel NULL pointer dereference at 0000000000000008 IP: newseg+0x10d/0x390 PGD cf8c1067 PUD cf8c2067 PMD 0 Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC CPU: 2 PID: 7636 Comm: trinity-child2 Not tainted 3.9.0+#67 ... Call Trace: ipcget+0x182/0x380 SyS_shmget+0x5a/0x60 tracesys+0xdd/0xe2 This bug was introduced by commit 37cbe899ba4a ("hugetlbfs: fix mmap failure in unaligned size request"). Reported-by: Dave Jones Cc: Signed-off-by: Li Zefan Reviewed-by: Naoya Horiguchi Acked-by: Rik van Riel Signed-off-by: Linus Torvalds --- 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 34af1fe34701a..7e199fa1960f8 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 1ae21d645c681..f681e1842fadc 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 -- 2.39.5