Commit 2ccd4f4d authored Jan 12, 2012 by Sasha Levin Committed by Linus Torvalds Jan 12, 2012

pipe: fail cleanly when root tries F_SETPIPE_SZ with big size



When a user with the CAP_SYS_RESOURCE cap tries to F_SETPIPE_SZ a pipe
with size bigger than kmalloc() can alloc it spits out an ugly warning:

  ------------[ cut here ]------------
  WARNING: at mm/page_alloc.c:2095 __alloc_pages_nodemask+0x5d3/0x7a0()
  Pid: 733, comm: a.out Not tainted 3.2.0-rc1+ #4
  Call Trace:
     warn_slowpath_common+0x75/0xb0
     warn_slowpath_null+0x15/0x20
     __alloc_pages_nodemask+0x5d3/0x7a0
     __get_free_pages+0x12/0x50
     __kmalloc+0x12b/0x150
     pipe_set_size+0x75/0x120
     pipe_fcntl+0xf8/0x140
     do_fcntl+0x2d4/0x410
     sys_fcntl+0x66/0xa0
     system_call_fastpath+0x16/0x1b
  ---[ end trace 432f702e6db7b5ee ]---

Instead, make kcalloc() handle the overflow case and fail quietly.

[akpm@linux-foundation.org: switch to sizeof(*bufs) for 80-column niceness]
Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Acked-by: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 888a214d

fs/pipe.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1137,7 +1137,7 @@ static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long nr_pages)
		if (nr_pages < pipe->nrbufs)
		return -EBUSY;

		bufs = kcalloc(nr_pages, sizeof(struct pipe_buffer), GFP_KERNEL);
		bufs = kcalloc(nr_pages, sizeof(*bufs), GFP_KERNEL \| __GFP_NOWARN);
		if (unlikely(!bufs))
		return -ENOMEM;

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