Commit 96e99be4 authored Feb 06, 2018 by Eric Biggers Committed by Linus Torvalds Feb 06, 2018

pipe: reject F_SETPIPE_SZ with size over UINT_MAX

A pipe's size is represented as an 'unsigned int'.  As expected, writing a
value greater than UINT_MAX to /proc/sys/fs/pipe-max-size fails with
EINVAL.  However, the F_SETPIPE_SZ fcntl silently truncates such values to
32 bits, rather than failing with EINVAL as expected.  (It *does* fail
with EINVAL for values above (1 << 31) but <= UINT_MAX.)

Fix this by moving the check against UINT_MAX into round_pipe_size() which
is called in both cases.

Link: http://lkml.kernel.org/r/20180111052902.14409-6-ebiggers3@gmail.com


Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: "Luis R . Rodriguez" <mcgrof@kernel.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 9903a91c

fs/pipe.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -1020,10 +1020,13 @@ const struct file_operations pipefifo_fops = {
		* Currently we rely on the pipe array holding a power-of-2 number
		* of pages. Returns 0 on error.
		*/
		unsigned int round_pipe_size(unsigned int size)
		unsigned int round_pipe_size(unsigned long size)
		{
		unsigned long nr_pages;

		if (size > UINT_MAX)
		return 0;

		/* Minimum pipe size, as required by POSIX */
		if (size < PAGE_SIZE)
		size = PAGE_SIZE;

include/linux/pipe_fs_i.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -190,6 +190,6 @@ long pipe_fcntl(struct file *, unsigned int, unsigned long arg);
		struct pipe_inode_info get_pipe_info(struct file file);

		int create_pipe_files(struct file **, int);
		unsigned int round_pipe_size(unsigned int size);
		unsigned int round_pipe_size(unsigned long size);

		#endif

kernel/sysctl.c

+0 −3

Original line number	Diff line number	Diff line
		@@ -2623,9 +2623,6 @@ static int do_proc_dopipe_max_size_conv(unsigned long *lvalp,
		if (write) {
		unsigned int val;

		if (*lvalp > UINT_MAX)
		return -EINVAL;

		val = round_pipe_size(*lvalp);
		if (val == 0)
		return -EINVAL;

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