[PATCH 2/3] mm: vmalloc: fix vmap_ram_vread_iter() return value

Arnd Bergmann
2023-03-23T11:59:46Z

The error handling in vmap_ram_vread_iter() can return an
uninitialized value in some cases:

mm/vmalloc.c:3539:6: error: variable 'remains' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
if (!vb)
^~~
mm/vmalloc.c:3587:17: note: uninitialized use occurs here
return count - remains + zero_iter(iter, remains);
^~~~~~~

Move the initialization up a few lines.

Fixes: d9cab54f7737 ("mm: vmalloc: convert vread() to vread_iter()")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
mm/vmalloc.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index ebfa1e9fe6f9..fb216495fe5a 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -3521,7 +3521,7 @@ static size_t vmap_ram_vread_iter(struct iov_iter *iter, const char *addr,
struct vmap_block *vb;
unsigned long offset;
unsigned int rs, re;
- size_t remains, n;
+ size_t remains = count, n;

/*
* If it's area created by vm_map_ram() interface directly, but
@@ -3545,7 +3545,6 @@ static size_t vmap_ram_vread_iter(struct iov_iter *iter, const char *addr,
goto finished_zero;
}

- remains = count;
for_each_set_bitrange(rs, re, vb->used_map, VMAP_BBMAP_BITS) {
size_t copied;

--
2.39.2