lm90_detect_nuvoton() is supposed to return NULL if it can not detect
a chip, or a pointer to the chip name if it does. Under some circumstances
it returns an error pointer instead. Some versions of gcc interpret an
ERR_PTR as region of size 0 and generate an error message.
In function ‘__fortify_strlen’,
inlined from ‘strlcpy’ at ./include/linux/fortify-string.h:159:10,
inlined from ‘lm90_detect’ at drivers/hwmon/lm90.c:2550:2:
./include/linux/fortify-string.h:50:33: error:
‘__builtin_strlen’ reading 1 or more bytes from a region of size 0
50 | #define __underlying_strlen __builtin_strlen
| ^
./include/linux/fortify-string.h:141:24: note:
in expansion of macro ‘__underlying_strlen’
141 | return __underlying_strlen(p);
| ^~~~~~~~~~~~~~~~~~~
Returning NULL instead of ERR_PTR() fixes the problem.
Fixes: c7cebce984a2 ("hwmon: (lm90) Rework detect function")
Reported-by: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
---
It is interesting that some versions of gcc interpret an ERR_PTR this way.
It did find a real bug, though the error message is quite confusing.
Would it be possible to enhance the fortify functions to detect a constant
ERR_PTR at compile time ? I think that might be quite useful.
drivers/hwmon/lm90.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/hwmon/lm90.c b/drivers/hwmon/lm90.c
index 03d07da8c2dc..221de01a327a 100644
--- a/drivers/hwmon/lm90.c
+++ b/drivers/hwmon/lm90.c
@@ -2321,7 +2321,7 @@ static const char *lm90_detect_nuvoton(struct i2c_client *client, int chip_id,
const char *name = NULL;
if (config2 < 0)
- return ERR_PTR(-ENODEV);
+ return NULL;
if (address == 0x4c && !(config1 & 0x2a) && !(config2 & 0xf8)) {
if (chip_id == 0x01 && convrate <= 0x09) {
--
2.36.2
