[PATCH][next] mm/shmem: Fix check on uninitialized pointer 'folio'

* [PATCH][next] mm/shmem: Fix check on uninitialized pointer 'folio'
@ 2022-05-04 13:21 Colin Ian King
  0 siblings, 0 replies; only message in thread
From: Colin Ian King @ 2022-05-04 13:21 UTC (permalink / raw)
  To: Hugh Dickins, Andrew Morton, Matthew Wilcox, linux-mm
  Cc: kernel-janitors, linux-kernel, llvm

In the case where shmem_swapin returns null, the jump to the error return
path via label 'failed' will end up with the uninitialized pointer folio
being null checked a few statements later. Fix this by ensuring folio is
initialized to null.

Detected by clang scan:
mm/shmem.c:1704:7: warning: variable 'folio' is used uninitialized
whenever 'if' condition is true [-Wsometimes-uninitialized]

Fixes: 2b58b3f33ba2 ("mm/shmem: convert shmem_swapin_page() to shmem_swapin_folio()")
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
---
 mm/shmem.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index 107f1e4dd0aa..7faaa61ff7fa 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1682,7 +1682,7 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
 	struct shmem_inode_info *info = SHMEM_I(inode);
 	struct mm_struct *charge_mm = vma ? vma->vm_mm : NULL;
 	struct page *page;
-	struct folio *folio;
+	struct folio *folio = NULL;
 	swp_entry_t swap;
 	int error;
 
-- 
2.35.1


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