2016-12-05 05:32:23

by Maninder Singh

Subject: [PATCH v3] mach-omap2: fixing wrong strcat for Non-NULL terminated string

Issue caught with static analysis tool:
"Dangerous usage of 'name' (strncpy doesn't always 0-terminate it)"

Use strlcpy _includes_ the NUL terminator, and strlcat() which ensures
that it won't overflow the buffer.

Reported-by: Maninder Singh <[email protected]>
Signed-off-by: Vaneet Narang <[email protected]>
Signed-off-by: Russell King <[email protected]>
---
v1 -> v2: changed strncpy to strlcpy
v2 -> v3: use of strlcat as suggested by Russell to
make change clearer and simpler.

arch/arm/mach-omap2/omap_hwmod.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/arm/mach-omap2/omap_hwmod.c b/arch/arm/mach-omap2/omap_hwmod.c
index 759e1d4..e8b9887 100644
--- a/arch/arm/mach-omap2/omap_hwmod.c
+++ b/arch/arm/mach-omap2/omap_hwmod.c
@@ -741,14 +741,14 @@ static int _init_main_clk(struct omap_hwmod *oh)
int ret = 0;
char name[MOD_CLK_MAX_NAME_LEN];
struct clk *clk;
+ static const char modck[] = "_mod_ck";

- /* +7 magic comes from '_mod_ck' suffix */
- if (strlen(oh->name) + 7 > MOD_CLK_MAX_NAME_LEN)
+ if (strlen(oh->name) >= MOD_CLK_MAX_NAME_LEN - strlen(modck))
pr_warn("%s: warning: cropping name for %s\n", __func__,
oh->name);

- strncpy(name, oh->name, MOD_CLK_MAX_NAME_LEN - 7);
- strcat(name, "_mod_ck");
+ strlcpy(name, oh->name, MOD_CLK_MAX_NAME_LEN - strlen(modck));
+ strlcat(name, modck, MOD_CLK_MAX_NAME_LEN);

clk = clk_get(NULL, name);
if (!IS_ERR(clk)) {
--
1.9.1

2016-12-06 17:08:08

by Tony Lindgren

Subject: Re: [PATCH v3] mach-omap2: fixing wrong strcat for Non-NULL terminated string

* Maninder Singh <[email protected]> [161204 21:32]:
> Issue caught with static analysis tool:
> "Dangerous usage of 'name' (strncpy doesn't always 0-terminate it)"
>
> Use strlcpy _includes_ the NUL terminator, and strlcat() which ensures
> that it won't overflow the buffer.
>
> Reported-by: Maninder Singh <[email protected]>
> Signed-off-by: Vaneet Narang <[email protected]>
> Signed-off-by: Russell King <[email protected]>

I think the above should have been just:

Cc: Russell King <[email protected]>

Can you please check and resend with Russell in Cc?

Regards,

Tony

> ---
> v1 -> v2: changed strncpy to strlcpy
> v2 -> v3: use of strlcat as suggested by Russell to
> make change clearer and simpler.
>
> arch/arm/mach-omap2/omap_hwmod.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm/mach-omap2/omap_hwmod.c b/arch/arm/mach-omap2/omap_hwmod.c
> index 759e1d4..e8b9887 100644
> --- a/arch/arm/mach-omap2/omap_hwmod.c
> +++ b/arch/arm/mach-omap2/omap_hwmod.c
> @@ -741,14 +741,14 @@ static int _init_main_clk(struct omap_hwmod *oh)
> int ret = 0;
> char name[MOD_CLK_MAX_NAME_LEN];
> struct clk *clk;
> + static const char modck[] = "_mod_ck";
>
> - /* +7 magic comes from '_mod_ck' suffix */
> - if (strlen(oh->name) + 7 > MOD_CLK_MAX_NAME_LEN)
> + if (strlen(oh->name) >= MOD_CLK_MAX_NAME_LEN - strlen(modck))
> pr_warn("%s: warning: cropping name for %s\n", __func__,
> oh->name);
>
> - strncpy(name, oh->name, MOD_CLK_MAX_NAME_LEN - 7);
> - strcat(name, "_mod_ck");
> + strlcpy(name, oh->name, MOD_CLK_MAX_NAME_LEN - strlen(modck));
> + strlcat(name, modck, MOD_CLK_MAX_NAME_LEN);
>
> clk = clk_get(NULL, name);
> if (!IS_ERR(clk)) {
> --
> 1.9.1
>