From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Dave Jones , Li Zefan , Naoya Horiguchi , Rik van Riel , Linus Torvalds Subject: [ 028/102] shm: fix null pointer deref when userspace specifies invalid hugepage size Date: Fri, 17 May 2013 14:35:43 -0700 Message-Id: <20130517213247.320521488@linuxfoundation.org> In-Reply-To: <20130517213244.277411019@linuxfoundation.org> References: <20130517213244.277411019@linuxfoundation.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Li Zefan commit 091d0d55b286c9340201b4ed4470be87fc568228 upstream. 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 af73e4d9506d ("hugetlbfs: fix mmap failure in unaligned size request"). Reported-by: Dave Jones Signed-off-by: Li Zefan Reviewed-by: Naoya Horiguchi Acked-by: Rik van Riel Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- ipc/shm.c | 8 +++++++- mm/mmap.c | 8 ++++++-- 2 files changed, 13 insertions(+), 3 deletions(-) --- a/ipc/shm.c +++ b/ipc/shm.c @@ -493,7 +493,13 @@ static int newseg(struct ipc_namespace * 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) --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1331,9 +1331,13 @@ SYSCALL_DEFINE6(mmap_pgoff, unsigned lon 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