Messages in this thread | | | Subject | Re: [PATCH 6/8] ASoC: intel: skylake: change snprintf to scnprintf for possible overflow | From | Pierre-Louis Bossart <> | Date | Wed, 16 Jan 2019 13:35:51 -0600 |
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>> diff --git a/sound/soc/intel/skylake/skl-debug.c b/sound/soc/intel/skylake/skl-debug.c >> index 5d7ac2ee7a3c..bb28db734fb7 100644 >> --- a/sound/soc/intel/skylake/skl-debug.c >> +++ b/sound/soc/intel/skylake/skl-debug.c >> @@ -43,7 +43,7 @@ static ssize_t skl_print_pins(struct skl_module_pin *m_pin, char *buf, >> ssize_t ret = 0; >> >> for (i = 0; i < max_pin; i++) >> - ret += snprintf(buf + size, MOD_BUF - size, >> + ret += scnprintf(buf + size, MOD_BUF - size, >> "%s %d\n\tModule %d\n\tInstance %d\n\t" >> "In-used %s\n\tType %s\n" >> "\tState %d\n\tIndex %d\n", >> > While working on a Coccinelle script to find more cases of this, I > noticed that this code is buggy: it keeps overwriting the same > position in the buf string: "buf + size" and don't take "ret" into > account at all. This needs to be: > > ret += scnprintf(buf + size + ret, MOD_BUF - size - ret,
Thanks for the sighting. Indeed this looks like a bug, all other calls to snprintf use "ret" to modify the destination/length.
The only explanation I have for it not being noticed earlier is that it's possibly not used - a 5mn test on 2 machines show the loop is actually not run (max_pin == 0).
It'll take me a bit of time to figure out what exactly this routine is supposed to do, maybe we should do the cross-tree change first?
-Pierre
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