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usb: gadget: f_uac1: Replace snprintf() with the safer scnprintf() variant

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There is a general misunderstanding amongst engineers that {v}snprintf()
returns the length of the data *actually* encoded into the destination
array.  However, as per the C99 standard {v}snprintf() really returns
the length of the data that *would have been* written if there were
enough space for it.  This misunderstanding has led to buffer-overruns
in the past.  It's generally considered safer to use the {v}scnprintf()
variants in their place (or even sprintf() in simple cases).  So let's
do that.

Link: https://lwn.net/Articles/69419/
Link: https://github.com/KSPP/linux/issues/105
Cc: Ruslan Bilovol <ruslan.bilovol@gmail.com>
Cc: Julian Scheel <julian@jusst.de>
Cc: Bryan Wu <cooloney@kernel.org>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20231213164246.1021885-3-lee@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Lee Jones 2023-12-13 16:42:31 +00:00 committed by Greg Kroah-Hartman
parent 0466e7e693
commit c1a371866d
1 changed files with 3 additions and 3 deletions
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6
drivers/usb/gadget/function/f_uac1.c
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@ -1634,7 +1634,7 @@ static ssize_t f_uac1_opts_##name##_show(struct config_item *item, \
int result; \
\
mutex_lock(&opts->lock); \
result = snprintf(page, sizeof(opts->name), "%s", opts->name); \
result = scnprintf(page, sizeof(opts->name), "%s", opts->name); \
mutex_unlock(&opts->lock); \
\
return result; \
@ -1652,7 +1652,7 @@ static ssize_t f_uac1_opts_##name##_store(struct config_item *item, \
goto end; \
} \
\
ret = snprintf(opts->name, min(sizeof(opts->name), len), \
ret = scnprintf(opts->name, min(sizeof(opts->name), len), \
"%s", page); \
\
end: \
@ -1758,7 +1758,7 @@ static struct usb_function_instance *f_audio_alloc_inst(void)
opts->req_number = UAC1_DEF_REQ_NUM;
snprintf(opts->function_name, sizeof(opts->function_name), "AC Interface");
scnprintf(opts->function_name, sizeof(opts->function_name), "AC Interface");
return &opts->func_inst;
}