From 2f52074d35135ecf3fb719f3430d72c17ae07287 Mon Sep 17 00:00:00 2001 From: Nicolas Iooss Date: Wed, 6 Sep 2017 16:19:01 -0700 Subject: [PATCH] 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@m4x.org Signed-off-by: Nicolas Iooss Reviewed-by: Ross Zwisler Cc: Matthew Wilcox Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/dax.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/dax.c b/fs/dax.c index 23674cda0b70..6afcacb3a87b 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -1230,7 +1230,7 @@ static int dax_pmd_insert_mapping(struct vm_fault *vmf, struct iomap *iomap, 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)