lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Sun, 15 Nov 2020 18:08:04 +0100
        Francis Laniel <>
Subject: [RESEND,net-next,PATCH v5 1/3] Fix unefficient call to memset before memcpu in nla_strlcpy.

From: Francis Laniel <>

Before this commit, nla_strlcpy first memseted dst to 0 then wrote src into it.
This is inefficient because bytes whom number is less than src length are written

This patch solves this issue by first writing src into dst then fill dst with
Note that, in the case where src length is higher than dst, only 0 is written.
Otherwise there are as many 0's written to fill dst.

For example, if src is "foo\0" and dst is 5 bytes long, the result will be:
1. "fooGG" after memcpy (G means garbage).
2. "foo\0\0" after memset.

Signed-off-by: Francis Laniel <>
Reviewed-by: Kees Cook <>
 lib/nlattr.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/nlattr.c b/lib/nlattr.c
index 74019c8ebf6b..07156e581997 100644
--- a/lib/nlattr.c
+++ b/lib/nlattr.c
@@ -731,8 +731,9 @@ size_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize)
 	if (dstsize > 0) {
 		size_t len = (srclen >= dstsize) ? dstsize - 1 : srclen;
-		memset(dst, 0, dstsize);
 		memcpy(dst, src, len);
+		/* Zero pad end of dst. */
+		memset(dst + len, 0, dstsize - len);
 	return srclen;

Powered by blists - more mailing lists