[PATCH][resend] Do not potentially overflow string in sumversion

From: Jesper Juhl
Date: Mon Mar 21 2011 - 15:18:18 EST

In scripts/mod/sumversion.c (in get_src_version()) we call
getenv("MODVERDIR"). This returns a pointer to a string of unknown length.
This string of unknown length we then pass on as an argument to sprintf()
and tell it to write the result to 'filelist' which has a, very much
fixed, size of 'PATH_MAX + 1'. If the string returned by getenv() is too
long we'll overrun the statically allocated buffer.
This patch prevents the buffer overrun by using snprintf() and telling it
to copy a maximum of 'PATH_MAX + 1' bytes (including the terminating \0).

Signed-off-by: Jesper Juhl <jj@xxxxxxxxxxxxx>
Acked-by: WANG Cong <xiyou.wangcong@xxxxxxxxx>
sumversion.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

compile tested only. Patch against Linus' tree as of right now.

diff --git
index 9dfcd6d..522c675 100644
--- a/scripts/mod/sumversion.c
+++ b/scripts/mod/sumversion.c
@@ -416,7 +416,7 @@ void get_src_version(const char *modname, char sum[], unsigned sumlen)
basename = strrchr(modname, '/') + 1;
basename = modname;
- sprintf(filelist, "%s/%.*s.mod", modverdir,
+ snprintf(filelist, PATH_MAX + 1, "%s/%.*s.mod", modverdir,
(int) strlen(basename) - 2, basename);

file = grab_file(filelist, &len);

Jesper Juhl <jj@xxxxxxxxxxxxx> http://www.chaosbits.net/
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