Commit 8e36709d authored Feb 10, 2006 by KAMEZAWA Hiroyuki Committed by Linus Torvalds Feb 10, 2006

[PATCH] shmdt cannot detach not-alined shm segment cleanly.



sys_shmdt() can manage shm segments which are covered by multiple vmas.  (This
can happen when a user uses mprotect() after shmat().)

This works well if shm is aligned to PAGE_SIZE, but if not, the last
segment cannot be detached.  It is because a comparison in sys_shmdt()

	(vma->vm_end - addr) < size
		addr == return address of shmat()
		size == shmsize, argments to shmget()

size should be aligned to PAGE_SIZE before being compared with vma->vm_end,
which is aligned.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Acked-by: Hugh Dickins <hugh@veritas.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

parent c22db941

ipc/shm.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -870,6 +870,7 @@ asmlinkage long sys_shmdt(char __user *shmaddr)
		* could possibly have landed at. Also cast things to loff_t to
		* prevent overflows and make comparisions vs. equal-width types.
		*/
		size = PAGE_ALIGN(size);
		while (vma && (loff_t)(vma->vm_end - addr) <= size) {
		next = vma->vm_next;

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