[slabinfo PATCH v2] Fix off-by-one buffer corruption after readlink() call

[Thomas Jarosch <thomas.jarosch@intra2net.com>]

readlink() never zero terminates the provided buffer.
Therefore we already do

    buffer[count] = 0;

This leads to an off-by-one buffer corruption as readlink()
might return the full size of the buffer.

The common technique is to reduce the buffer size by one.
Another fix would be to check

"
if (count < 0 || count == sizeof(buffer))
    fatal();
"

Reducing the buffer size by one is easier IMHO.

Signed-off-by: Thomas Jarosch <thomas.jarosch@intra2net.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Christoph Lameter <cl@gentwo.org>
---
 tools/slub/slabinfo.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/tools/slub/slabinfo.c b/tools/slub/slabinfo.c
index 868cc93..cc1a378 100644
--- a/tools/slub/slabinfo.c
+++ b/tools/slub/slabinfo.c
@@ -1145,7 +1145,7 @@ static void read_slab_dir(void)
 		switch (de->d_type) {
 		   case DT_LNK:
 			alias->name = strdup(de->d_name);
-			count = readlink(de->d_name, buffer, sizeof(buffer));
+			count = readlink(de->d_name, buffer, sizeof(buffer)-1);
 
 			if (count < 0)
 				fatal("Cannot read symlink %s\n", de->d_name);
-- 
1.7.6.4