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authorChristoph Hellwig <hch@lst.de>2020-09-07 10:27:00 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-09-07 10:46:35 +0200
commitab04de8ec235ab03573e7ef33b21c357ba248b5f (patch)
treeb6e2bfa2e0bd3d867228412ce203c7f589f7245f /drivers/char
parent947bece14b741ed339eda14db42cf3c357183501 (diff)
/dev/zero: fixups for ->read
Reported the cleared bytes in case of a partial clear_user instead of -EFAULT, and remove a pointless conditional, as cleared must be non-zero by the time we hit the signal_pending check. Reported-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20200907082700.2057137-1-hch@lst.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/char')
-rw-r--r--drivers/char/mem.c12
1 files changed, 9 insertions, 3 deletions
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 1dc99ab15845..94c2b556cf97 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -733,14 +733,20 @@ static ssize_t read_zero(struct file *file, char __user *buf,
while (count) {
size_t chunk = min_t(size_t, count, PAGE_SIZE);
+ size_t left;
- if (clear_user(buf + cleared, chunk))
- return cleared ? cleared : -EFAULT;
+ left = clear_user(buf + cleared, chunk);
+ if (unlikely(left)) {
+ cleared += (chunk - left);
+ if (!cleared)
+ return -EFAULT;
+ break;
+ }
cleared += chunk;
count -= chunk;
if (signal_pending(current))
- return cleared ? cleared : -ERESTARTSYS;
+ break;
cond_resched();
}