From: Davidlohr Bueso Date: Wed, 11 Sep 2013 21:26:28 +0000 (-0700) Subject: ipc, shm: guard against non-existant vma in shmdt(2) X-Git-Tag: v3.12-rc1~52^2~4 X-Git-Url: http://pileus.org/git/?a=commitdiff_plain;h=530fcd16d87cd2417c472a581ba5a1e501556c86;p=~andy%2Flinux ipc, shm: guard against non-existant vma in shmdt(2) When !CONFIG_MMU there's a chance we can derefence a NULL pointer when the VM area isn't found - check the return value of find_vma(). Also, remove the redundant -EINVAL return: retval is set to the proper return code and *only* changed to 0, when we actually unmap the segments. Signed-off-by: Davidlohr Bueso Cc: Sedat Dilek Cc: Rik van Riel Cc: Manfred Spraul Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/ipc/shm.c b/ipc/shm.c index cb2cedaa880..a0ed957cefc 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -1288,8 +1288,7 @@ SYSCALL_DEFINE1(shmdt, char __user *, shmaddr) #else /* CONFIG_MMU */ /* under NOMMU conditions, the exact address to be destroyed must be * given */ - retval = -EINVAL; - if (vma->vm_start == addr && vma->vm_ops == &shm_vm_ops) { + if (vma && vma->vm_start == addr && vma->vm_ops == &shm_vm_ops) { do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start); retval = 0; }