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authorMarkus Armbruster <armbru@redhat.com>2008-02-26 09:57:11 -0600
committerEric Van Hensbergen <ericvh@opteron.9grid.us>2008-05-14 19:23:25 -0500
commitb32a09db4fb9a87246ba4e7726a979ac4709ad97 (patch)
treeb84cf43745c329ccbcbd2671da91e729db8132ca /lib/parser.c
parentdd286422fefdcff784e8d336deeb88ce817e14db (diff)
downloadlinux-sh-b32a09db4fb9a87246ba4e7726a979ac4709ad97.tar.gz
add match_strlcpy() us it to make v9fs make uname and remotename parsing more robust
match_strcpy() is a somewhat creepy function: the caller needs to make sure that the destination buffer is big enough, and when he screws up or forgets, match_strcpy() happily overruns the buffer. There's exactly one customer: v9fs_parse_options(). I believe it currently can't overflow its buffer, but that's not exactly obvious. The source string is a substing of the mount options. The kernel silently truncates those to PAGE_SIZE bytes, including the terminating zero. See compat_sys_mount() and do_mount(). The destination buffer is obtained from __getname(), which allocates from name_cachep, which is initialized by vfs_caches_init() for size PATH_MAX. We're safe as long as PATH_MAX <= PAGE_SIZE. PATH_MAX is 4096. As far as I know, the smallest PAGE_SIZE is also 4096. Here's a patch that makes the code a bit more obviously correct. It doesn't depend on PATH_MAX <= PAGE_SIZE. Signed-off-by: Markus Armbruster <armbru@redhat.com> Cc: Latchesar Ionkov <lucho@ionkov.net> Cc: Jim Meyering <meyering@redhat.com> Cc: "Randy.Dunlap" <rdunlap@xenotime.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
Diffstat (limited to 'lib/parser.c')
-rw-r--r--lib/parser.c32
1 files changed, 20 insertions, 12 deletions
diff --git a/lib/parser.c b/lib/parser.c
index 703c8c13b346..4f0cbc03e0e8 100644
--- a/lib/parser.c
+++ b/lib/parser.c
@@ -182,18 +182,25 @@ int match_hex(substring_t *s, int *result)
}
/**
- * match_strcpy: - copies the characters from a substring_t to a string
- * @to: string to copy characters to.
- * @s: &substring_t to copy
+ * match_strlcpy: - Copy the characters from a substring_t to a sized buffer
+ * @dest: where to copy to
+ * @src: &substring_t to copy
+ * @size: size of destination buffer
*
- * Description: Copies the set of characters represented by the given
- * &substring_t @s to the c-style string @to. Caller guarantees that @to is
- * large enough to hold the characters of @s.
+ * Description: Copy the characters in &substring_t @src to the
+ * c-style string @dest. Copy no more than @size - 1 characters, plus
+ * the terminating NUL. Return length of @src.
*/
-void match_strcpy(char *to, const substring_t *s)
+size_t match_strlcpy(char *dest, const substring_t *src, size_t size)
{
- memcpy(to, s->from, s->to - s->from);
- to[s->to - s->from] = '\0';
+ size_t ret = src->to - src->from;
+
+ if (size) {
+ size_t len = ret >= size ? size - 1 : ret;
+ memcpy(dest, src->from, len);
+ dest[len] = '\0';
+ }
+ return ret;
}
/**
@@ -206,9 +213,10 @@ void match_strcpy(char *to, const substring_t *s)
*/
char *match_strdup(const substring_t *s)
{
- char *p = kmalloc(s->to - s->from + 1, GFP_KERNEL);
+ size_t sz = s->to - s->from + 1;
+ char *p = kmalloc(sz, GFP_KERNEL);
if (p)
- match_strcpy(p, s);
+ match_strlcpy(p, s, sz);
return p;
}
@@ -216,5 +224,5 @@ EXPORT_SYMBOL(match_token);
EXPORT_SYMBOL(match_int);
EXPORT_SYMBOL(match_octal);
EXPORT_SYMBOL(match_hex);
-EXPORT_SYMBOL(match_strcpy);
+EXPORT_SYMBOL(match_strlcpy);
EXPORT_SYMBOL(match_strdup);