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    SubjectRe: [PATCHv2] ceph: Fix error handling in ceph_read_iter
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    On 10/10/2016 04:11 PM, Yan, Zheng wrote:
    >
    >> On 10 Oct 2016, at 20:56, Nikolay Borisov <kernel@kyup.com> wrote:
    >>
    >> In case __ceph_do_getattr returns an error and the retry_op in
    >> ceph_read_iter is not READ_INLINE, then it's possible to invoke
    >> __free_page on a page which is NULL, this naturally leads to a crash.
    >> This can happen when, for example, a process waiting on a MDS reply
    >> receives sigterm.
    >>
    >> Fix this by explicitly checking whether the page is set or not.
    >>
    >> Signed-off-by: Nikolay Borisov <kernel@kyup.com>
    >> Link: http://www.spinics.net/lists/ceph-users/msg31592.html
    >> ---
    >>
    >> Inverted the condition, so resending with correct condition
    >> this time.
    >>
    >> fs/ceph/file.c | 3 ++-
    >> 1 file changed, 2 insertions(+), 1 deletion(-)
    >>
    >> diff --git a/fs/ceph/file.c b/fs/ceph/file.c
    >> index 3c68e6aee2f0..7413313ae6c8 100644
    >> --- a/fs/ceph/file.c
    >> +++ b/fs/ceph/file.c
    >> @@ -929,7 +929,8 @@ again:
    >> statret = __ceph_do_getattr(inode, page,
    >> CEPH_STAT_CAP_INLINE_DATA, !!page);
    >> if (statret < 0) {
    >> - __free_page(page);
    >> + if (page)
    >> + __free_page(page);
    >> if (statret == -ENODATA) {
    >> BUG_ON(retry_op != READ_INLINE);
    >> goto again;
    >> —
    > Reviewed-by: Yan, Zheng <zyan@redhat.com>

    I believe this needs to also be tagged as stable. To whomever is going
    to merge it: can you please do that?


    >
    >> 2.5.0
    >>
    >

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