[v2] ErrHandling:Make IS_ERR_VALUE_U32 as generic API to avoid IS_ERR_VALUE abuses.

IS_ERR_VALUE() assumes that its parameter is an unsigned long.
It can not be used to check if an 'unsigned int' reflects an error.
As they pass an 'unsigned int' into a function that takes an
'unsigned long' argument. This happens to work because the type
is sign-extended on 64-bit architectures before it gets converted
into an unsigned type.

However, anything that passes an 'unsigned short' or 'unsigned int'
argument into IS_ERR_VALUE() is guaranteed to be broken, as are
8-bit integers and types that are wider than 'unsigned long'.

It would be nice to any users that are not passing 'unsigned int'
arguments.

Signed-off-by: Arvind Yadav <redacted>
---
 drivers/bcma/scan.c | 1 -
 include/linux/err.h | 2 ++
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/bcma/scan.c b/drivers/bcma/scan.c
index 4a2d1b2..3bc77eb 100644
--- a/drivers/bcma/scan.c
+++ b/drivers/bcma/scan.c

@@ -272,7 +272,6 @@ static struct bcma_device *bcma_find_core_reverse(struct bcma_bus *bus, u16 core
 	return NULL;
 }
 
-#define IS_ERR_VALUE_U32(x) ((x) >= (u32)-MAX_ERRNO)
 
 static int bcma_get_next_core(struct bcma_bus *bus, u32 __iomem **eromptr,
 			      struct bcma_device_id *match, int core_num,

diff --git a/include/linux/err.h b/include/linux/err.h
index 1e35588..e05a63d 100644
--- a/include/linux/err.h
+++ b/include/linux/err.h

@@ -20,6 +20,8 @@
 
 #define IS_ERR_VALUE(x) unlikely((unsigned long)(void *)(x) >= (unsigned long)-MAX_ERRNO)
 
+#define IS_ERR_VALUE_U32(x) unlikely((unsigned int)(x) >= (unsigned int)-MAX_ERRNO)
+
 static inline void * __must_check ERR_PTR(long error)
 {
 	return (void *) error;

-- 
1.9.1

Arvind Yadav [off-list ref] wrote:

IS_ERR_VALUE() assumes that its parameter is an unsigned long.
It can not be used to check if an 'unsigned int' reflects an error.
As they pass an 'unsigned int' into a function that takes an
'unsigned long' argument. This happens to work because the type
is sign-extended on 64-bit architectures before it gets converted
into an unsigned type.

However, anything that passes an 'unsigned short' or 'unsigned int'
argument into IS_ERR_VALUE() is guaranteed to be broken, as are
8-bit integers and types that are wider than 'unsigned long'.

It would be nice to any users that are not passing 'unsigned int'
arguments.

Signed-off-by: Arvind Yadav <redacted>

This touches include/linux/err.h and I'm not very enthusiastic to change
anything in include directory without wider support. I recommend first to just
fix bcma.  And separately you can try to improve linux/err.h via some more
approariate tree, not via wireless trees.

-- 
Sent by pwcli
https://patchwork.kernel.org/patch/9222139/