From: Vitaly Mayatskikh <v.mayatskih@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: Thomas Tuttle <ttuttle@google.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: [PATCH] pagemap: require aligned-length, non-null reads of /proc/pid/pagemap
Date: Mon, 20 Apr 2009 16:58:32 +0200 [thread overview]
Message-ID: <87eivn5q3r.wl%vmayatsk@redhat.com> (raw)
The intention of commit aae8679b0ebcaa92f99c1c3cb0cd651594a43915 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>
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 39e4ad4..6f61b7c 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;
--
wbr, Vitaly
reply other threads:[~2009-04-20 14:58 UTC|newest]
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