On 17.06.25 13:58, Jiri Olsa wrote:
ping
On Wed, Jun 11, 2025 at 10:57:08AM +0200, Jiri Olsa wrote:
hi, ping ;-)
On Wed, Jun 04, 2025 at 10:28:42PM +0200, Jiri Olsa wrote:
On Wed, May 14, 2025 at 12:18:09PM +0200, Jiri Olsa wrote:
From: Jiri Olsa <olsaj...@gmail.com>
There's error path that could lead to inactive uprobe:
1) uprobe_register succeeds - updates instruction to int3 and
changes ref_ctr from 0 to 1
2) uprobe_unregister fails - int3 stays in place, but ref_ctr
is changed to 0 (it's not restored to 1 in the fail path)
uprobe is leaked
3) another uprobe_register comes and re-uses the leaked uprobe
and succeds - but int3 is already in place, so ref_ctr update
is skipped and it stays 0 - uprobe CAN NOT be triggered now
4) uprobe_unregister fails because ref_ctr value is unexpected
Fixing this by reverting the updated ref_ctr value back to 1 in step 2),
which is the case when uprobe_unregister fails (int3 stays in place),
but we have already updated refctr.
The new scenario will go as follows:
1) uprobe_register succeeds - updates instruction to int3 and
changes ref_ctr from 0 to 1
2) uprobe_unregister fails - int3 stays in place and ref_ctr
is reverted to 1.. uprobe is leaked
3) another uprobe_register comes and re-uses the leaked uprobe
and succeds - but int3 is already in place, so ref_ctr update
is skipped and it stays 1 - uprobe CAN be triggered now
4) uprobe_unregister succeeds
Fixes: 1cc33161a83d ("uprobes: Support SDT markers having reference count
(semaphore)")
Acked-by: David Hildenbrand <da...@redhat.com>
Acked-by: Oleg Nesterov <o...@redhat.com>
Suggested-by: Oleg Nesterov <o...@redhat.com>
Signed-off-by: Jiri Olsa <jo...@kernel.org>
hi,
I can't find this in any related tree, was this pulled in?
@Andrew, I assume you should pick this.
--
Cheers,
David / dhildenb
