3.13-stable review patch. If anyone has any objections, please let me know.
------------------
From: Al Viro <v...@zeniv.linux.org.uk>
commit e825196d48d2b89a6ec3a8eff280098d2a78207e upstream.
In all callchains leading to prepend_name(), the value left in *buflen
is eventually discarded unused if prepend_name() has returned a negative.
So we are free to do what prepend() does, and subtract from *buflen
*before* checking for underflow (which turns into checking the sign
of subtraction result, of course).
Signed-off-by: Al Viro <v...@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
fs/dcache.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2833,9 +2833,9 @@ static int prepend_name(char **buffer, i
u32 dlen = ACCESS_ONCE(name->len);
char *p;
- if (*buflen < dlen + 1)
- return -ENAMETOOLONG;
*buflen -= dlen + 1;
+ if (*buflen < 0)
+ return -ENAMETOOLONG;
p = *buffer -= dlen + 1;
*p++ = '/';
while (dlen--) {
--
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