lkml.org 
[lkml]   [2019]   [Sep]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 4.19 05/93] fs: afs: Fix a possible null-pointer dereference in afs_put_read()
    Date
    [ Upstream commit a6eed4ab5dd4bfb696c1a3f49742b8d1846a66a0 ]

    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.

    Fixes: f3ddee8dc4e2 ("afs: Fix directory handling")
    Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
    Signed-off-by: David Howells <dhowells@redhat.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    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 7d4f26198573d..843d3b970b845 100644
    --- a/fs/afs/file.c
    +++ b/fs/afs/file.c
    @@ -193,11 +193,13 @@ 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);
    }
    }
    --
    2.20.1


    \
     
     \ /
      Last update: 2019-09-04 20:06    [W:2.792 / U:0.144 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site