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usb: gadget: f_uac2: Replace snprintf() with the safer scnprintf() variant

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[ Upstream commit 60034e0aedf507888c4a880f57011bb7f5d7700c ]

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: James Gruber <jimmyjgruber@gmail.com>
Cc: Yadwinder Singh <yadi.brar01@gmail.com>
Cc: Jaswinder Singh <jaswinder.singh@linaro.org>
Cc: Ruslan Bilovol <ruslan.bilovol@gmail.com>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20231213164246.1021885-4-lee@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Stable-dep-of: 9499327714de ("usb: gadget: f_uac2: fix return value for UAC2_ATTRIBUTE_STRING store")
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Lee Jones
2023-12-13 16:42:32 +00:00
committed by Greg Kroah-Hartman
parent ec9b965459
commit 158833b519
1 changed files with 3 additions and 3 deletions
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6
drivers/usb/gadget/function/f_uac2.c
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@@ -2042,7 +2042,7 @@ static ssize_t f_uac2_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; \
@@ -2060,7 +2060,7 @@ static ssize_t f_uac2_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: \
@@ -2178,7 +2178,7 @@ static struct usb_function_instance *afunc_alloc_inst(void)
opts->req_number = UAC2_DEF_REQ_NUM;
opts->fb_max = FBACK_FAST_MAX;
snprintf(opts->function_name, sizeof(opts->function_name), "Source/Sink");
scnprintf(opts->function_name, sizeof(opts->function_name), "Source/Sink");
return &opts->func_inst;
}