lkml.org 
[lkml]   [2014]   [Oct]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v5 10/12] fs: dcache: manually unpoison dname after allocation to shut up kasan's reports
Date
We need to manually unpoison rounded up allocation size for dname
to avoid kasan's reports in dentry_string_cmp().
When CONFIG_DCACHE_WORD_ACCESS=y dentry_string_cmp may access
few bytes beyound requested in kmalloc() size.

dentry_string_cmp() relates on that fact that dentry allocated
using kmalloc and kmalloc internally round up allocation size.
So this is not a bug, but this makes kasan to complain about
such accesses.
To avoid such reports we mark rounded up allocation size in
shadow as accessible.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com>
---
fs/dcache.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/fs/dcache.c b/fs/dcache.c
index d5a23fd..d58ffcc6 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -38,6 +38,8 @@
#include <linux/prefetch.h>
#include <linux/ratelimit.h>
#include <linux/list_lru.h>
+#include <linux/kasan.h>
+
#include "internal.h"
#include "mount.h"

@@ -1429,6 +1431,10 @@ struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name)
}
atomic_set(&p->u.count, 1);
dname = p->name;
+#ifdef CONFIG_DCACHE_WORD_ACCESS
+ kasan_unpoison_shadow(dname,
+ round_up(name->len + 1, sizeof(unsigned long)));
+#endif
} else {
dname = dentry->d_iname;
}
--
2.1.2


\
 
 \ /
  Last update: 2014-10-27 18:21    [W:1.298 / U:0.736 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site