Messages in this thread | | | Subject | Re: [Xen-devel] [PATCH] xen-blkfront: fix kernel panic with negotiate_mq error path | From | Manjunath Patil <> | Date | Tue, 30 Oct 2018 09:27:43 -0700 |
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Thank you Juergen for your comments.
I will soon send v2 patch.
-Thanks, Manjunath On 10/30/2018 12:04 AM, Juergen Gross wrote: > On 29/10/2018 19:31, Manjunath Patil wrote: >> info->nr_rings isn't adjusted in case of ENOMEM error from >> negotiate_mq(). This leads to kernel panic in error path. >> >> Typical call stack involving panic - >> #8 page_fault at ffffffff8175936f >> [exception RIP: blkif_free_ring+33] >> RIP: ffffffffa0149491 RSP: ffff8804f7673c08 RFLAGS: 00010292 >> ... >> #9 blkif_free at ffffffffa0149aaa [xen_blkfront] >> #10 talk_to_blkback at ffffffffa014c8cd [xen_blkfront] >> #11 blkback_changed at ffffffffa014ea8b [xen_blkfront] >> #12 xenbus_otherend_changed at ffffffff81424670 >> #13 backend_changed at ffffffff81426dc3 >> #14 xenwatch_thread at ffffffff81422f29 >> #15 kthread at ffffffff810abe6a >> #16 ret_from_fork at ffffffff81754078 >> >> Though either of my changes avoid the panic, I included both the >> changes. This issue got introduced with "7ed8ce1 xen-blkfront: move >> negotiate_mq to cover all cases of new VBDs" > Please us the correct format for specifying another commit. > >> Signed-off-by: Manjunath Patil <manjunath.b.patil@oracle.com> > Can you please add a "Fixes:" tag and "Cc: stable@vger.kernel.org" ? > >> --- >> drivers/block/xen-blkfront.c | 7 +++++-- >> 1 files changed, 5 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c >> index 429d201..dc8fe25 100644 >> --- a/drivers/block/xen-blkfront.c >> +++ b/drivers/block/xen-blkfront.c >> @@ -1350,8 +1350,10 @@ static void blkif_free(struct blkfront_info *info, int suspend) >> if (info->rq) >> blk_mq_stop_hw_queues(info->rq); >> >> - for (i = 0; i < info->nr_rings; i++) >> - blkif_free_ring(&info->rinfo[i]); >> + if (info->rinfo) { >> + for (i = 0; i < info->nr_rings; i++) >> + blkif_free_ring(&info->rinfo[i]); >> + } > I'd drop this change. > >> >> kfree(info->rinfo); >> info->rinfo = NULL; >> @@ -1919,6 +1921,7 @@ static int negotiate_mq(struct blkfront_info *info) >> GFP_KERNEL); >> if (!info->rinfo) { >> xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info structure"); >> + info->nr_rings = 0; >> return -ENOMEM; >> } > > Juergen >
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