Messages in this thread Patch in this message | | | Date | Sun, 5 Nov 2023 05:36:41 -0800 | From | Richard Cochran <> | Subject | Re: [PATCH net-next V6] ptp: fix corrupted list in ptp_open |
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Edward!
On Sun, Nov 05, 2023 at 10:12:08AM +0800, Edward Adam Davis wrote: > There is no lock protection when writing ptp->tsevqs in ptp_open() and > ptp_release(), which can cause data corruption, use spin lock to avoid this > issue. > > Moreover, ptp_release() should not be used to release the queue in ptp_read(), > and it should be deleted together.
Change to: "it should be deleted altogether"
> Reported-and-tested-by: syzbot+df3f3ef31f60781fa911@syzkaller.appspotmail.com > Fixes: 8f5de6fb2453 ("ptp: support multiple timestamp event readers") > Signed-off-by: Edward Adam Davis <eadavis@qq.com> > --- > drivers/ptp/ptp_chardev.c | 11 +++++++---- > drivers/ptp/ptp_clock.c | 1 + > drivers/ptp/ptp_private.h | 1 + > 3 files changed, 9 insertions(+), 4 deletions(-) > > diff --git a/drivers/ptp/ptp_chardev.c b/drivers/ptp/ptp_chardev.c > index 282cd7d24077..31594f40a21e 100644 > --- a/drivers/ptp/ptp_chardev.c > +++ b/drivers/ptp/ptp_chardev.c > @@ -108,6 +108,7 @@ int ptp_open(struct posix_clock_context *pccontext, fmode_t fmode) > container_of(pccontext->clk, struct ptp_clock, clock); > struct timestamp_event_queue *queue; > char debugfsname[32]; > + unsigned long flags; > > queue = kzalloc(sizeof(*queue), GFP_KERNEL); > if (!queue) > @@ -119,8 +120,10 @@ int ptp_open(struct posix_clock_context *pccontext, fmode_t fmode) > } > bitmap_set(queue->mask, 0, PTP_MAX_CHANNELS); > spin_lock_init(&queue->lock); > + spin_lock_irqsave(&ptp->tsevqs_lock, flags); > list_add_tail(&queue->qlist, &ptp->tsevqs); > pccontext->private_clkdata = queue;
Move this assignment outside of locked region, i.e. after spin_unlock_irqrestore().
> + spin_unlock_irqrestore(&ptp->tsevqs_lock, flags); > > /* Debugfs contents */ > sprintf(debugfsname, "0x%p", queue); > @@ -139,13 +142,15 @@ int ptp_release(struct posix_clock_context *pccontext) > { > struct timestamp_event_queue *queue = pccontext->private_clkdata; > unsigned long flags; > + struct ptp_clock *ptp = > + container_of(pccontext->clk, struct ptp_clock, clock); > > if (queue) {
Please remove this test. Since you removed ptp_release() from ptp_read(), the queue cannot be NULL.
> debugfs_remove(queue->debugfs_instance); > + spin_lock_irqsave(&ptp->tsevqs_lock, flags); > pccontext->private_clkdata = NULL;
Move this assignment outside of locked region.
> - spin_lock_irqsave(&queue->lock, flags); > list_del(&queue->qlist); > - spin_unlock_irqrestore(&queue->lock, flags); > + spin_unlock_irqrestore(&ptp->tsevqs_lock, flags); > bitmap_free(queue->mask); > kfree(queue); > } > @@ -585,7 +590,5 @@ ssize_t ptp_read(struct posix_clock_context *pccontext, uint rdflags, > free_event: > kfree(event); > exit: > - if (result < 0) > - ptp_release(pccontext);
This is good, but please put it into a separate patch, along with the removal of the bogus "if (queue)" test in ptp_release().
> return result; > } > diff --git a/drivers/ptp/ptp_clock.c b/drivers/ptp/ptp_clock.c > index 3d1b0a97301c..ea82648ad557 100644 > --- a/drivers/ptp/ptp_clock.c > +++ b/drivers/ptp/ptp_clock.c > @@ -247,6 +247,7 @@ struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info, > if (!queue) > goto no_memory_queue; > list_add_tail(&queue->qlist, &ptp->tsevqs); > + spin_lock_init(&ptp->tsevqs_lock); > queue->mask = bitmap_alloc(PTP_MAX_CHANNELS, GFP_KERNEL); > if (!queue->mask) > goto no_memory_bitmap; > diff --git a/drivers/ptp/ptp_private.h b/drivers/ptp/ptp_private.h > index 52f87e394aa6..63af246f17eb 100644 > --- a/drivers/ptp/ptp_private.h > +++ b/drivers/ptp/ptp_private.h > @@ -44,6 +44,7 @@ struct ptp_clock { > struct pps_device *pps_source; > long dialed_frequency; /* remembers the frequency adjustment */ > struct list_head tsevqs; /* timestamp fifo list */ > + spinlock_t tsevqs_lock; /* one process at a time writing the timestamp fifo list*/
Please change this comment to "protects tsevqs from concurrent access"
> struct mutex pincfg_mux; /* protect concurrent info->pin_config access */ > wait_queue_head_t tsev_wq; > int defunct; /* tells readers to go away when clock is being removed */ > -- > 2.25.1 >
Since v6.6 now contains the original commit, please change subject to [net].
Thanks, Richard
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