From: Jim Meyering <jim@meyering.net>
Date: Thu, 26 Apr 2012 16:35:12 +0000 (+0200)
Subject: Btrfs: avoid buffer overrun in btrfs_printk
X-Git-Tag: v3.5-rc1~17^2~1^2~22
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=f07c9a79f06cd33b1c9c2c4eacb60bafa7e3f310;p=platform%2Fkernel%2Flinux-exynos.git

Btrfs: avoid buffer overrun in btrfs_printk

The buffer read-overrun would be triggered by a printk format
starting with <N>, where N is a single digit.  NUL-terminate
after strncpy.  Use memcpy, not strncpy, since we know the
string we're copying fits in the destination buffer and
contains no NUL byte.

Signed-off-by: Jim Meyering <meyering@redhat.com>
---

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 2cd3217..46b2665 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -188,7 +188,8 @@ void btrfs_printk(struct btrfs_fs_info *fs_info, const char *fmt, ...)
 	va_start(args, fmt);
 
 	if (fmt[0] == '<' && isdigit(fmt[1]) && fmt[2] == '>') {
-		strncpy(lvl, fmt, 3);
+		memcpy(lvl, fmt, 3);
+		lvl[3] = '\0';
 		fmt += 3;
 		type = logtypes[fmt[1] - '0'];
 	} else