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Subject[ 115/184] sysfs: sysfs_pathname/sysfs_add_one: Use strlcat()
2.6.32-longterm review patch.  If anyone has any objections, please let me know.

------------------
instead of strcat()

From: Geert Uytterhoeven <geert@linux-m68k.org>

commit 66081a72517a131430dcf986775f3268aafcb546 upstream.

The warning check for duplicate sysfs entries can cause a buffer overflow
when printing the warning, as strcat() doesn't check buffer sizes.
Use strlcat() instead.

Since strlcat() doesn't return a pointer to the passed buffer, unlike
strcat(), I had to convert the nested concatenation in sysfs_add_one() to
an admittedly more obscure comma operator construct, to avoid emitting code
for the concatenation if CONFIG_BUG is disabled.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>
---
fs/sysfs/dir.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index e020183..5e7279a 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -440,20 +440,18 @@ int __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
/**
* sysfs_pathname - return full path to sysfs dirent
* @sd: sysfs_dirent whose path we want
- * @path: caller allocated buffer
+ * @path: caller allocated buffer of size PATH_MAX
*
* Gives the name "/" to the sysfs_root entry; any path returned
* is relative to wherever sysfs is mounted.
- *
- * XXX: does no error checking on @path size
*/
static char *sysfs_pathname(struct sysfs_dirent *sd, char *path)
{
if (sd->s_parent) {
sysfs_pathname(sd->s_parent, path);
- strcat(path, "/");
+ strlcat(path, "/", PATH_MAX);
}
- strcat(path, sd->s_name);
+ strlcat(path, sd->s_name, PATH_MAX);
return path;
}

@@ -486,9 +484,11 @@ int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
char *path = kzalloc(PATH_MAX, GFP_KERNEL);
WARN(1, KERN_WARNING
"sysfs: cannot create duplicate filename '%s'\n",
- (path == NULL) ? sd->s_name :
- strcat(strcat(sysfs_pathname(acxt->parent_sd, path), "/"),
- sd->s_name));
+ (path == NULL) ? sd->s_name
+ : (sysfs_pathname(acxt->parent_sd, path),
+ strlcat(path, "/", PATH_MAX),
+ strlcat(path, sd->s_name, PATH_MAX),
+ path));
kfree(path);
}

--
1.7.12.2.21.g234cd45.dirty




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