UAC1 and UAC2 configfs rate-list attributes parse a comma-separated
list of sampling rates and store each parsed value in fixed-size arrays.
The arrays have UAC_MAX_RATES entries, but the store paths do not check
that the input contains at most that many tokens before writing through
opts->name##s[i++].

Writing more than ten rates therefore writes past the end of the
p_srates[] or c_srates[] array in struct f_uac1_opts or struct
f_uac2_opts.

With CONFIG_UBSAN_BOUNDS enabled, writing an 11-entry rate list to the
UAC1 p_srate attribute reports:

  UBSAN: array-index-out-of-bounds
  drivers/usb/gadget/function/f_uac1.c:1669:1
  index 10 is out of range for type 'int [10]'
  __ubsan_handle_out_of_bounds.cold
  f_uac1_opts_p_srate_store
  configfs_write_iter
  vfs_write
  ksys_write
  do_syscall_64

The same reproducer against the UAC2 p_srate attribute reports:

  UBSAN: array-index-out-of-bounds
  drivers/usb/gadget/function/f_uac2.c:2087:1
  index 10 is out of range for type 'int [10]'
  __ubsan_handle_out_of_bounds.cold
  f_uac2_opts_p_srate_store
  configfs_write_iter
  vfs_write
  ksys_write
  do_syscall_64

Reject additional tokens once UAC_MAX_RATES entries have been parsed.
Also keep the original kstrdup() pointer for kfree(), because strsep()
advances the parsing cursor. Freeing the advanced cursor leaks the
original buffer on successful parses and can free an interior pointer on
some error paths.

Fixes: 695d39ffc2b5 ("usb: gadget: f_uac1: Support multiple sampling rates")
Fixes: a7339e4f5788 ("usb: gadget: f_uac2: Support multiple sampling rates")
Signed-off-by: Qing Ming <a0yami@mailbox.org>
---
 drivers/usb/gadget/function/f_uac1.c | 13 +++++++++----
 drivers/usb/gadget/function/f_uac2.c | 13 +++++++++----
 2 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/drivers/usb/gadget/function/f_uac1.c b/drivers/usb/gadget/function/f_uac1.c
index 85c502e98f57..7a81cd176abd 100644
--- a/drivers/usb/gadget/function/f_uac1.c
+++ b/drivers/usb/gadget/function/f_uac1.c
@@ -1594,7 +1594,8 @@ static ssize_t f_uac1_opts_##name##_store(struct config_item *item,	\
 					  const char *page, size_t len)	\
 {									\
 	struct f_uac1_opts *opts = to_f_uac1_opts(item);		\
-	char *split_page = NULL;					\
+	char *buf = NULL;						\
+	char *split_page;						\
 	int ret = -EINVAL;						\
 	char *token;							\
 	u32 num;							\
@@ -1608,18 +1609,22 @@ static ssize_t f_uac1_opts_##name##_store(struct config_item *item,	\
 									\
 	i = 0;								\
 	memset(opts->name##s, 0x00, sizeof(opts->name##s));		\
-	split_page = kstrdup(page, GFP_KERNEL);				\
+	buf = kstrdup(page, GFP_KERNEL);				\
+	split_page = buf;						\
 	while ((token = strsep(&split_page, ",")) != NULL) {		\
 		ret = kstrtou32(token, 0, &num);			\
 		if (ret)						\
 			goto end;					\
-									\
+		if (i >= UAC_MAX_RATES) {				\
+			ret = -EINVAL;					\
+			goto end;					\
+		}							\
 		opts->name##s[i++] = num;				\
 		ret = len;						\
 	};								\
 									\
 end:									\
-	kfree(split_page);						\
+	kfree(buf);							\
 	mutex_unlock(&opts->lock);					\
 	return ret;							\
 }									\
diff --git a/drivers/usb/gadget/function/f_uac2.c b/drivers/usb/gadget/function/f_uac2.c
index 897787d0803c..d8cf710085a0 100644
--- a/drivers/usb/gadget/function/f_uac2.c
+++ b/drivers/usb/gadget/function/f_uac2.c
@@ -2012,7 +2012,8 @@ static ssize_t f_uac2_opts_##name##_store(struct config_item *item,	\
 					  const char *page, size_t len)	\
 {									\
 	struct f_uac2_opts *opts = to_f_uac2_opts(item);		\
-	char *split_page = NULL;					\
+	char *buf = NULL;						\
+	char *split_page;						\
 	int ret = -EINVAL;						\
 	char *token;							\
 	u32 num;							\
@@ -2026,18 +2027,22 @@ static ssize_t f_uac2_opts_##name##_store(struct config_item *item,	\
 									\
 	i = 0;								\
 	memset(opts->name##s, 0x00, sizeof(opts->name##s));		\
-	split_page = kstrdup(page, GFP_KERNEL);				\
+	buf = kstrdup(page, GFP_KERNEL);				\
+	split_page = buf;						\
 	while ((token = strsep(&split_page, ",")) != NULL) {		\
 		ret = kstrtou32(token, 0, &num);			\
 		if (ret)						\
 			goto end;					\
-									\
+		if (i >= UAC_MAX_RATES) {				\
+			ret = -EINVAL;					\
+			goto end;					\
+		}							\
 		opts->name##s[i++] = num;				\
 		ret = len;						\
 	};								\
 									\
 end:									\
-	kfree(split_page);						\
+	kfree(buf);							\
 	mutex_unlock(&opts->lock);					\
 	return ret;							\
 }									\
-- 
2.53.0