From 44c5e1c1fa9df3815786a78b8c5ac7ec9c12202a Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Tue, 6 Feb 2018 15:42:00 -0800 Subject: [PATCH] pipe: reject F_SETPIPE_SZ with size over UINT_MAX commit 96e99be40e4cff870a83233731121ec0f7f95075 upstream. 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 Acked-by: Kees Cook Acked-by: Joe Lawrence Cc: Alexander Viro Cc: "Luis R . Rodriguez" Cc: Michael Kerrisk Cc: Mikulas Patocka Cc: Willy Tarreau Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Ben Hutchings --- fs/pipe.c | 5 ++++- include/linux/pipe_fs_i.h | 2 +- kernel/sysctl.c | 3 --- 3 files changed, 5 insertions(+), 5 deletions(-) diff --git a/fs/pipe.c b/fs/pipe.c index 9fa8d82ce54d..f75284e22b1b 100644 --- a/fs/pipe.c +++ b/fs/pipe.c @@ -1008,10 +1008,13 @@ 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; diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h index 3f342d78afdf..eed87a0fdc5c 100644 --- a/include/linux/pipe_fs_i.h +++ b/include/linux/pipe_fs_i.h @@ -148,6 +148,6 @@ 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 diff --git a/kernel/sysctl.c b/kernel/sysctl.c index a4f15c232afc..e714622b6fa9 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -2230,9 +2230,6 @@ static int do_proc_dopipe_max_size_conv(bool *negp, unsigned long *lvalp, if (write) { unsigned int val; - if (*lvalp > UINT_MAX) - return -EINVAL; - val = round_pipe_size(*lvalp); if (*negp || val == 0) return -EINVAL;