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authorBernd Edlinger <bernd.edlinger@hotmail.de>2018-07-07 17:52:47 +0000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-09-16 22:38:57 +0200
commita75e78f21f9ad4b810868c89dbbabcc3931591ca (patch)
tree5f2d9f66299b62c9fea792a499a152f205ff26a3
parentbdae566d5d9733b6e32b378668b84eadf28a94d4 (diff)
kernfs: Fix range checks in kernfs_get_target_path
The terminating NUL byte is only there because the buffer is allocated with kzalloc(PAGE_SIZE, GFP_KERNEL), but since the range-check is off-by-one, and PAGE_SIZE==PATH_MAX, the returned string may not be zero-terminated if it is exactly PATH_MAX characters long. Furthermore also the initial loop may theoretically exceed PATH_MAX and cause a fault. Signed-off-by: Bernd Edlinger <bernd.edlinger@hotmail.de> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--fs/kernfs/symlink.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/fs/kernfs/symlink.c b/fs/kernfs/symlink.c
index 305b220af45d..162f43b80c84 100644
--- a/fs/kernfs/symlink.c
+++ b/fs/kernfs/symlink.c
@@ -72,6 +72,9 @@ static int kernfs_get_target_path(struct kernfs_node *parent,
if (base == kn)
break;
+ if ((s - path) + 3 >= PATH_MAX)
+ return -ENAMETOOLONG;
+
strcpy(s, "../");
s += 3;
base = base->parent;
@@ -88,7 +91,7 @@ static int kernfs_get_target_path(struct kernfs_node *parent,
if (len < 2)
return -EINVAL;
len--;
- if ((s - path) + len > PATH_MAX)
+ if ((s - path) + len >= PATH_MAX)
return -ENAMETOOLONG;
/* reverse fillup of target string from target to base */