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| author | Steven Rostedt <rostedt@goodmis.org> | 2009-09-18 13:05:42 -0700 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2009-09-24 07:47:22 -0400 |
| commit | 14be27460e4722d7135de3c46d043b4fc4382247 (patch) | |
| tree | d7026e0e43c1f048f2a0f31a54beb93b91b5fb89 /fs/libfs.c | |
| parent | 94a8d5caba74211ec76dac80fc6e2d5c391530df (diff) | |
| download | lwn-14be27460e4722d7135de3c46d043b4fc4382247.tar.gz lwn-14be27460e4722d7135de3c46d043b4fc4382247.zip | |
libfs: make simple_read_from_buffer conventional
Impact: have simple_read_from_buffer conform to standards
It was brought to my attention by Andrew Morton, Theodore Tso, and H.
Peter Anvin that a read from userspace should only return -EFAULT if
nothing was actually read.
Looking at the simple_read_from_buffer I noticed that this function does
not conform to that rule. This patch fixes that function.
[akpm@linux-foundation.org: simplification suggested by hpa]
[hpa@zytor.com: fix count==0 handling]
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/libfs.c')
| -rw-r--r-- | fs/libfs.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/fs/libfs.c b/fs/libfs.c index dcec3d3ea64f..662a28e4f667 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -527,14 +527,18 @@ ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos, const void *from, size_t available) { loff_t pos = *ppos; + size_t ret; + if (pos < 0) return -EINVAL; - if (pos >= available) + if (pos >= available || !count) return 0; if (count > available - pos) count = available - pos; - if (copy_to_user(to, from + pos, count)) + ret = copy_to_user(to, from + pos, count); + if (ret == count) return -EFAULT; + count -= ret; *ppos = pos + count; return count; } |