Re: [PATCH v2] net/tun: fix ioctl() based info leaks
From: Eric Dumazet <hidden>
Date: 2012-07-30 06:22:26
On Mon, 2012-07-30 at 07:45 +0200, Mathias Krause wrote:
quoted hunk ↗ jump to hunk
The tun module leaks up to 36 bytes of memory by not fully initializing a structure located on the stack that gets copied to user memory by the TUNGETIFF and SIOCGIFHWADDR ioctl()s. Signed-off-by: Mathias Krause <redacted> --- v2: - removed braces around else branch - minor adjustment of the commit message drivers/net/tun.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 987aeef..01255ff 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c@@ -1252,9 +1252,11 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd, int vnet_hdr_sz; int ret; - if (cmd == TUNSETIFF || _IOC_TYPE(cmd) == 0x89) + if (cmd == TUNSETIFF || _IOC_TYPE(cmd) == 0x89) { if (copy_from_user(&ifr, argp, ifreq_len)) return -EFAULT; + } else + memset(&ifr, 0, sizeof(ifr)); if (cmd == TUNGETFEATURES) { /* Currently this just means: "what IFF flags are valid?".
Actually braces were better
vi +169 Documentation/CodingStyle
This does not apply if only one branch of a conditional statement is a
single
statement; in the latter case use braces in both branches:
if (condition) {
do_this();
do_that();
} else {
otherwise();
}