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Subject[PATCH] reiserfs : fix improper free in reiserfs_get_block
Date
From: Tom Rix <trix@redhat.com>

clang static analysis flags this error

inode.c:1083:5: warning: Argument to kfree() is the address of the
local variable 'unf_single', which is not memory allocated by
malloc() [unix.Malloc]
kfree(un);
^~~~~~~~~
Assignment of 'un'

/*
* We use this in case we need to allocate
* only one block which is a fastpath
*/
unp_t unf_single = 0;

...

if (blocks_needed == 1) {
un = &unf_single;
} else {
un = kcalloc(min(blocks_needed, max_to_insert),
UNFM_P_SIZE, GFP_NOFS);
if (!un) {
un = &unf_single;
blocks_needed = 1;
max_to_insert = 0;
}
}

The logic to free 'un'

if (blocks_needed != 1)
kfree(un);

Because the kcalloc failure falls back to using unf_single,
the if-check for the free is wrong.

So improve the check.

Signed-off-by: Tom Rix <trix@redhat.com>
---
fs/reiserfs/inode.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/reiserfs/inode.c b/fs/reiserfs/inode.c
index 1509775da040..4d62148e43e6 100644
--- a/fs/reiserfs/inode.c
+++ b/fs/reiserfs/inode.c
@@ -1079,7 +1079,7 @@ int reiserfs_get_block(struct inode *inode, sector_t block,
UNFM_P_SIZE *
blocks_needed);

- if (blocks_needed != 1)
+ if (un != &unf_single)
kfree(un);

if (retval) {
--
2.18.1
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