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| author | Vitaly Mayatskikh <v.mayatskih@gmail.com> | 2009-04-30 15:08:18 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2009-05-08 14:54:34 -0700 |
| commit | c7273beb2266d3058ef299e2135be7edce5cd03f (patch) | |
| tree | a2c1ae91a7e843c93a87ec8b1b990623a69248ab | |
| parent | f3fb397564e99368f0979933c6ee5fe2d3887668 (diff) | |
| download | lwn-c7273beb2266d3058ef299e2135be7edce5cd03f.tar.gz lwn-c7273beb2266d3058ef299e2135be7edce5cd03f.zip | |
pagemap: require aligned-length, non-null reads of /proc/pid/pagemap
commit 0816178638c15ce5472d39d771a96860dff4141a upstream.
The intention of commit aae8679b0ebcaa92f99c1c3cb0cd651594a43915
("pagemap: fix bug in add_to_pagemap, require aligned-length reads of
/proc/pid/pagemap") was to force reads of /proc/pid/pagemap to be a
multiple of 8 bytes, but now it allows to read 0 bytes, which actually
puts some data to user's buffer. According to POSIX, if count is zero,
read() should return zero and has no other results.
Signed-off-by: Vitaly Mayatskikh <v.mayatskih@gmail.com>
Cc: Thomas Tuttle <ttuttle@google.com>
Acked-by: Matt Mackall <mpm@selenic.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | fs/proc/task_mmu.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 8b84227b0c44..c7f64a9f11b1 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -665,6 +665,10 @@ static ssize_t pagemap_read(struct file *file, char __user *buf, goto out_task; ret = 0; + + if (!count) + goto out_task; + mm = get_task_mm(task); if (!mm) goto out_task; |