* [PATCH] fs: afs: Fix a possible null-pointer dereference in afs_put_read()
@ 2019-07-23 12:25 Jia-Ju Bai
2019-07-30 15:40 ` David Howells
0 siblings, 1 reply; 2+ messages in thread
From: Jia-Ju Bai @ 2019-07-23 12:25 UTC (permalink / raw)
To: dhowells; +Cc: linux-afs, linux-kernel, Jia-Ju Bai
In afs_read_dir(), there is an if statement on line 255 to check whether
req->pages is NULL:
if (!req->pages)
goto error;
If req->pages is NULL, afs_put_read() on line 337 is executed.
In afs_put_read(), req->pages[i] is used on line 195.
Thus, a possible null-pointer dereference may occur in this case.
To fix this possible bug, an if statement is added in afs_put_read() to
check req->pages.
This bug is found by a static analysis tool STCheck written by us.
Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
---
fs/afs/file.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/fs/afs/file.c b/fs/afs/file.c
index 56b69576274d..dd3c55c9101c 100644
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -191,11 +191,13 @@ void afs_put_read(struct afs_read *req)
int i;
if (refcount_dec_and_test(&req->usage)) {
- for (i = 0; i < req->nr_pages; i++)
- if (req->pages[i])
- put_page(req->pages[i]);
- if (req->pages != req->array)
- kfree(req->pages);
+ if (req->pages) {
+ for (i = 0; i < req->nr_pages; i++)
+ if (req->pages[i])
+ put_page(req->pages[i]);
+ if (req->pages != req->array)
+ kfree(req->pages);
+ }
kfree(req);
}
}
--
2.17.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] fs: afs: Fix a possible null-pointer dereference in afs_put_read()
2019-07-23 12:25 [PATCH] fs: afs: Fix a possible null-pointer dereference in afs_put_read() Jia-Ju Bai
@ 2019-07-30 15:40 ` David Howells
0 siblings, 0 replies; 2+ messages in thread
From: David Howells @ 2019-07-30 15:40 UTC (permalink / raw)
To: Jia-Ju Bai; +Cc: dhowells, linux-afs, linux-kernel
This is in my afs-fixes branch.
David
^ permalink raw reply [flat|nested] 2+ messages in thread
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2019-07-23 12:25 [PATCH] fs: afs: Fix a possible null-pointer dereference in afs_put_read() Jia-Ju Bai
2019-07-30 15:40 ` David Howells
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