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authorVitaly Mayatskikh <v.mayatskih@gmail.com>2009-04-30 15:08:18 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-05-02 15:36:09 -0700
commit0816178638c15ce5472d39d771a96860dff4141a (patch)
tree9db0c3d2192286e818e6f6827fda3602b7d5a466
parentb827e496c893de0c0f142abfaeb8730a2fd6b37f (diff)
pagemap: require aligned-length, non-null reads of /proc/pid/pagemap
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>
-rw-r--r--fs/proc/task_mmu.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 39e4ad4f59f..6f61b7cc32e 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;