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authorAl Viro <viro@zeniv.linux.org.uk>2014-03-23 00:28:40 -0400
committerJiri Slaby <jslaby@suse.cz>2014-04-03 10:32:29 +0200
commita41fd7536d9cbc81cf02033c3efa4078431fa4d0 (patch)
tree24c826b660b08f78a65b20ec46b807a26b9f849e
parent2c611dc0ca77c8012fee6f33cf05040b16dbee38 (diff)
make prepend_name() work correctly when called with negative *buflen
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 <viro@zeniv.linux.org.uk> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
-rw-r--r--fs/dcache.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/dcache.c b/fs/dcache.c
index 4021e0172602..30b38e23caa7 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2846,9 +2846,9 @@ static int prepend_name(char **buffer, int *buflen, struct qstr *name)
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--) {