----- Original Message -----
Hi Bob, hi Greg,
On Fri, Sep 11, 2020 at 08:49:14AM -0400, Bob Peterson wrote:
----- Original Message -----
On Fri, Sep 11, 2020 at 08:08:35AM -0400, Bob Peterson wrote:
----- Original Message -----
On Thu, Sep 10, 2020 at 09:43:19PM +0200, Salvatore Bonaccorso wrote:
Hi,
On Tue, Jun 23, 2020 at 09:57:50PM +0200, Greg Kroah-Hartman wrote: > From: Bob Peterson rpeterso@redhat.com > > [ Upstream commit 83d060ca8d90fa1e3feac227f995c013100862d3 ] > > Before this patch, transactions could be merged into the system > transaction by function gfs2_merge_trans(), but the transaction > ail > lists were never merged. Because the ail flushing mechanism can > run > separately, bd elements can be attached to the transaction's > buffer > list during the transaction (trans_add_meta, etc) but quickly > moved > to its ail lists. Later, in function gfs2_trans_end, the > transaction > can be freed (by gfs2_trans_end) while it still has bd elements > queued to its ail lists, which can cause it to either lose track > of > the bd elements altogether (memory leak) or worse, reference the > bd > elements after the parent transaction has been freed. > > Although I've not seen any serious consequences, the problem > becomes > apparent with the previous patch's addition of: > > gfs2_assert_warn(sdp, list_empty(&tr->tr_ail1_list)); > > to function gfs2_trans_free(). > > This patch adds logic into gfs2_merge_trans() to move the merged > transaction's ail lists to the sdp transaction. This prevents the > use-after-free. To do this properly, we need to hold the ail > lock, > so we pass sdp into the function instead of the transaction > itself. > > Signed-off-by: Bob Peterson rpeterso@redhat.com > Signed-off-by: Andreas Gruenbacher agruenba@redhat.com > Signed-off-by: Sasha Levin sashal@kernel.org
(snip)
In Debian two user confirmed issues on writing on a GFS2 partition with this commit applied. The initial Debian report is at https://bugs.debian.org/968567 and Daniel Craig reported it into Bugzilla at https://bugzilla.kernel.org/show_bug.cgi?id=209217 .
Writing to a gfs2 filesystem fails and results in a soft lookup of the machine for kernels with that commit applied. I cannot reporduce the issue myself due not having a respective setup available, but Daniel described a minimal serieos of steps to reproduce the issue.
This might affect as well other stable series where this commit was applied, as there was a similar report for someone running 5.4.58 in https://www.redhat.com/archives/linux-cluster/2020-August/msg00000.html
Can you report this to the gfs2 developers?
thanks,
greg k-h
Hi Greg,
No need. The patch came from the gfs2 developers. I think he just wants it added to a stable release.
What commit needs to be added to a stable release?
confused,
greg k-h
Sorry Greg,
It's pretty early here and the caffeine hadn't quite hit my system. The problem is most likely that 4.19.132 is missing this upstream patch:
cbcc89b630447ec7836aa2b9242d9bb1725f5a61
I'm not sure how or why 83d060ca8d90fa1e3feac227f995c013100862d3 got put into stable without a stable CC but cbcc89b6304 is definitely required.
I'd like to suggest Salvatore try cherry-picking this patch to see if it fixes the problem, and if so, perhaps Greg can add it to stable.
I can confirm (Daniel was able to test): Applying cbcc89b63044 ("gfs2: initialize transaction tr_ailX_lists earlier") fixes the issue. So would be great if you can pick that up for stable for those series which had 83d060ca8d90 ("gfs2: fix use-after-free on transaction ail lists") as well.
Regards, Salvatore
Hi Greg,
As per Salvatore's email above, can you please cherry-pick GFS2 patch cbcc89b630447ec7836aa2b9242d9bb1725f5a61 to the stable releases like 4.19 to which ("gfs2: fix use-after-free on transaction ail lists") (83d060ca8d90fa1e3feac227f995c013100862d3) was applied? Thanks.
Regards,
Bob Peterson GFS2 File System