From: Azeem Shaikh <azeemshaikh38@gmail.com>
To: Maxim Krasnyansky <maxk@qti.qualcomm.com>,
Richard Weinberger <richard@nod.at>,
Anton Ivanov <anton.ivanov@cambridgegreys.com>,
Johannes Berg <johannes@sipsolutions.net>
Cc: linux-hardening@vger.kernel.org,
Azeem Shaikh <azeemshaikh38@gmail.com>,
linux-kernel@vger.kernel.org, linux-um@lists.infradead.org,
"Jason A. Donenfeld" <Jason@zx2c4.com>
Subject: [PATCH v3] uml: Replace strlcpy with strscpy
Date: Wed, 14 Jun 2023 00:36:04 +0000 [thread overview]
Message-ID: <20230614003604.1021205-1-azeemshaikh38@gmail.com> (raw)
strlcpy() reads the entire source buffer first.
This read may exceed the destination size limit.
This is both inefficient and can lead to linear read
overflows if a source string is not NUL-terminated [1].
In an effort to remove strlcpy() completely [2], replace
strlcpy() here with strscpy().
No return values were used, so direct replacement is safe.
[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] https://github.com/KSPP/linux/issues/89
Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>
---
v1: https://lore.kernel.org/all/20230530164004.986750-1-azeemshaikh38@gmail.com/
v2: https://lore.kernel.org/all/20230606182410.3976487-1-azeemshaikh38@gmail.com/
Changes from v1 - added strscpy declaration. v1 does not build.
Changes from v2 - removed Reported-By: and Closes: tag from commit log.
arch/um/include/shared/user.h | 1 +
arch/um/os-Linux/drivers/tuntap_user.c | 2 +-
2 files changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/um/include/shared/user.h b/arch/um/include/shared/user.h
index bda66e5a9d4e..0347a190429c 100644
--- a/arch/um/include/shared/user.h
+++ b/arch/um/include/shared/user.h
@@ -52,6 +52,7 @@ static inline int printk(const char *fmt, ...)
extern int in_aton(char *str);
extern size_t strlcpy(char *, const char *, size_t);
extern size_t strlcat(char *, const char *, size_t);
+extern size_t strscpy(char *, const char *, size_t);
/* Copied from linux/compiler-gcc.h since we can't include it directly */
#define barrier() __asm__ __volatile__("": : :"memory")
diff --git a/arch/um/os-Linux/drivers/tuntap_user.c b/arch/um/os-Linux/drivers/tuntap_user.c
index 53eb3d508645..2284e9c1cbbb 100644
--- a/arch/um/os-Linux/drivers/tuntap_user.c
+++ b/arch/um/os-Linux/drivers/tuntap_user.c
@@ -146,7 +146,7 @@ static int tuntap_open(void *data)
}
memset(&ifr, 0, sizeof(ifr));
ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
- strlcpy(ifr.ifr_name, pri->dev_name, sizeof(ifr.ifr_name));
+ strscpy(ifr.ifr_name, pri->dev_name, sizeof(ifr.ifr_name));
if (ioctl(pri->fd, TUNSETIFF, &ifr) < 0) {
err = -errno;
printk(UM_KERN_ERR "TUNSETIFF failed, errno = %d\n",
--
2.41.0.rc0.172.g3f132b7071-goog
next reply other threads:[~2023-06-14 0:36 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-14 0:36 Azeem Shaikh [this message]
2023-06-20 20:28 ` [PATCH v3] uml: Replace strlcpy with strscpy Kees Cook
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