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Re: [Qemu-devel] [PATCH] linux-user: Check sscanf return value in open_n
From: |
Philippe Mathieu-Daudé |
Subject: |
Re: [Qemu-devel] [PATCH] linux-user: Check sscanf return value in open_net_route() |
Date: |
Tue, 5 Feb 2019 21:26:48 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 |
On 2/5/19 6:42 PM, Peter Maydell wrote:
> Coverity warns (CID 1390634) that open_net_route() is not
> checking the return value from sscanf(), which means that
> it might then use values that aren't initialized.
>
> Errors here should in general not happen since we're passing
> an assumed-good /proc/net/route from the host kernel, but
> if we do fail to parse a line then just skip it in the output
> we pass to the guest.
>
> Signed-off-by: Peter Maydell <address@hidden>
Reviewed-by: Philippe Mathieu-Daudé <address@hidden>
> ---
> linux-user/syscall.c | 12 +++++++++---
> 1 file changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index b5786d4fc1f..894678aa8b4 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -6762,9 +6762,15 @@ static int open_net_route(void *cpu_env, int fd)
> char iface[16];
> uint32_t dest, gw, mask;
> unsigned int flags, refcnt, use, metric, mtu, window, irtt;
> - sscanf(line, "%s\t%08x\t%08x\t%04x\t%d\t%d\t%d\t%08x\t%d\t%u\t%u\n",
> - iface, &dest, &gw, &flags, &refcnt, &use, &metric,
> - &mask, &mtu, &window, &irtt);
> + int fields;
> +
> + fields = sscanf(line,
> +
> "%s\t%08x\t%08x\t%04x\t%d\t%d\t%d\t%08x\t%d\t%u\t%u\n",
> + iface, &dest, &gw, &flags, &refcnt, &use, &metric,
> + &mask, &mtu, &window, &irtt);
> + if (fields != 11) {
> + continue;
> + }
> dprintf(fd, "%s\t%08x\t%08x\t%04x\t%d\t%d\t%d\t%08x\t%d\t%u\t%u\n",
> iface, tswap32(dest), tswap32(gw), flags, refcnt, use,
> metric, tswap32(mask), mtu, window, irtt);
>