From: Nicolas Iooss <nicolas.iooss_linux@xxxxxxx>
Subject: dax: initialize variable pfn before using it
dax_pmd_insert_mapping() contains the following code:
pfn_t pfn;
if (bdev_dax_pgoff(bdev, sector, size, &pgoff) != 0)
goto fallback;
/* ... */
fallback:
trace_dax_pmd_insert_mapping_fallback(inode, vmf, length, pfn, ret);
When the condition in the if statement fails, the function calls
trace_dax_pmd_insert_mapping_fallback() with an uninitialized pfn value.
This issue has been found while building the kernel with clang. The
compiler reported:
fs/dax.c:1280:6: error: variable 'pfn' is used uninitialized
whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
if (bdev_dax_pgoff(bdev, sector, size, &pgoff) != 0)
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
fs/dax.c:1310:60: note: uninitialized use occurs here
trace_dax_pmd_insert_mapping_fallback(inode, vmf, length, pfn, ret);
^~~
Link: http://lkml.kernel.org/r/20170903083000.587-1-nicolas.iooss_linux@xxxxxxx
Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@xxxxxxx>
Reviewed-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
Cc: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/dax.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN fs/dax.c~dax-initialize-variable-pfn-before-using-it fs/dax.c
--- a/fs/dax.c~dax-initialize-variable-pfn-before-using-it
+++ a/fs/dax.c
@@ -1230,7 +1230,7 @@ static int dax_pmd_insert_mapping(struct
void *ret = NULL, *kaddr;
long length = 0;
pgoff_t pgoff;
- pfn_t pfn;
+ pfn_t pfn = {};
int id;
if (bdev_dax_pgoff(bdev, sector, size, &pgoff) != 0)
_
--
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