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Subject[PATCH 1/2] CacheFiles: Fix memory leak in cachefiles_check_auxdata error paths
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From: Josh Boyer <jwboyer@redhat.com>

In cachefiles_check_auxdata(), we allocate auxbuf but fail to free it if we
determine there's an error or that the data is stale.

Further, assigning the output of vfs_getxattr() to auxbuf->len gives problems
with checking for errors as auxbuf->len is a u16. We don't actually need to
set auxbuf->len, so keep the length in a variable for now. We shouldn't need
to check the upper limit of the buffer as an overflow there should be
indicated by -ERANGE.

Whilst we're at it, fscache_check_aux() returns an enum value, not an int, so
assign it to an appropriately typed variable rather than to ret.

Signed-off-by: Josh Boyer <jwboyer@fedoraproject.org>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Hongyi Jia <jiayisuse@gmail.com>
cc: Milosz Tanski <milosz@adfin.com>
---

fs/cachefiles/xattr.c | 29 +++++++++++++++--------------
1 file changed, 15 insertions(+), 14 deletions(-)

diff --git a/fs/cachefiles/xattr.c b/fs/cachefiles/xattr.c
index 34c88b8..12b0eef 100644
--- a/fs/cachefiles/xattr.c
+++ b/fs/cachefiles/xattr.c
@@ -162,8 +162,9 @@ int cachefiles_update_object_xattr(struct cachefiles_object *object,
int cachefiles_check_auxdata(struct cachefiles_object *object)
{
struct cachefiles_xattr *auxbuf;
+ enum fscache_checkaux validity;
struct dentry *dentry = object->dentry;
- unsigned int dlen;
+ ssize_t xlen;
int ret;

ASSERT(dentry);
@@ -174,22 +175,22 @@ int cachefiles_check_auxdata(struct cachefiles_object *object)
if (!auxbuf)
return -ENOMEM;

- auxbuf->len = vfs_getxattr(dentry, cachefiles_xattr_cache,
- &auxbuf->type, 512 + 1);
- if (auxbuf->len < 1)
- return -ESTALE;
-
- if (auxbuf->type != object->fscache.cookie->def->type)
- return -ESTALE;
+ xlen = vfs_getxattr(dentry, cachefiles_xattr_cache,
+ &auxbuf->type, 512 + 1);
+ ret = -ESTALE;
+ if (xlen < 1 ||
+ auxbuf->type != object->fscache.cookie->def->type)
+ goto error;

- dlen = auxbuf->len - 1;
- ret = fscache_check_aux(&object->fscache, &auxbuf->data, dlen);
+ xlen--;
+ validity = fscache_check_aux(&object->fscache, &auxbuf->data, xlen);
+ if (validity != FSCACHE_CHECKAUX_OKAY)
+ goto error;

+ ret = 0;
+error:
kfree(auxbuf);
- if (ret != FSCACHE_CHECKAUX_OKAY)
- return -ESTALE;
-
- return 0;
+ return ret;
}

/*


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