[PATCH] mpssd: fix buffer overflow warning

[PATCH] mpssd: fix buffer overflow warning

[Mike Danese]

The compilation emits a warning in function ‘snprintf’,
    inlined from ‘set_cmdline’ at
    ../Documentation/mic/mpssd/mpssd.c:1541:9:
/usr/include/x86_64-linux-gnu/bits/stdio2.h:64:10:
    warning: call to __builtin___snprintf_chk will always overflow
    destination buffer

This was introduced in commit f4a66c204482 ("misc: mic: Update MIC host
daemon with COSM changes") and is fixed by reverting the changes to the
size argument of these snprintf statements.

Cc: Ashutosh Dixit <ashutosh.dixit@intel.com>
Signed-off-by: Mike Danese <mikedanese@google.com>
---
 Documentation/mic/mpssd/mpssd.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Documentation/mic/mpssd/mpssd.c b/Documentation/mic/mpssd/mpssd.c
index 30fb842..49db1de 100644
--- a/Documentation/mic/mpssd/mpssd.c
+++ b/Documentation/mic/mpssd/mpssd.c
@@ -1538,9 +1538,9 @@ set_cmdline(struct mic_info *mic)
 
 	len = snprintf(buffer, PATH_MAX,
 		"clocksource=tsc highres=off nohz=off ");
-	len += snprintf(buffer + len, PATH_MAX,
+	len += snprintf(buffer + len, PATH_MAX - len,
 		"cpufreq_on;corec6_off;pc3_off;pc6_off ");
-	len += snprintf(buffer + len, PATH_MAX,
+	len += snprintf(buffer + len, PATH_MAX - len,
 		"ifcfg=static;address,172.31.%d.1;netmask,255.255.255.0",
 		mic->id + 1);
 
-- 
2.5.0

Re: [PATCH] mpssd: fix buffer overflow warning

[Ashutosh Dixit]

On Fri, May 20 2016 at 12:54:51 AM, Mike Danese <mikedanese@google.com> wrote:
> The compilation emits a warning in function ‘snprintf’,
>     inlined from ‘set_cmdline’ at
>     ../Documentation/mic/mpssd/mpssd.c:1541:9:
> /usr/include/x86_64-linux-gnu/bits/stdio2.h:64:10:
>     warning: call to __builtin___snprintf_chk will always overflow
>     destination buffer
>
> This was introduced in commit f4a66c204482 ("misc: mic: Update MIC host
> daemon with COSM changes") and is fixed by reverting the changes to the
> size argument of these snprintf statements.

Thanks for the patch, the fix is fine.

Re: [PATCH] mpssd: fix buffer overflow warning

[Jonathan Corbet]

On Thu, 19 May 2016 21:54:51 -0700
Mike Danese <mikedanese@google.com> wrote:

> The compilation emits a warning in function ‘snprintf’,
>     inlined from ‘set_cmdline’ at
>     ../Documentation/mic/mpssd/mpssd.c:1541:9:
> /usr/include/x86_64-linux-gnu/bits/stdio2.h:64:10:
>     warning: call to __builtin___snprintf_chk will always overflow
>     destination buffer

Applied to the docs tree, thanks.  I do wonder if Documentation/ is the
best place for this tool, though...

jon