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| author | Jann Horn <jannh@google.com> | 2024-12-18 17:56:25 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-12-27 13:58:55 +0100 |
| commit | a73f0425f44ba087751d8e0fa5738f6cd3adf7b9 (patch) | |
| tree | ac6af32ee10d5e2faf61fb07ef30e4a6b1565b97 /io_uring | |
| parent | 24047899f94ee696a1c62988d52b955d457b584e (diff) | |
| download | linux-a73f0425f44ba087751d8e0fa5738f6cd3adf7b9.tar.gz linux-a73f0425f44ba087751d8e0fa5738f6cd3adf7b9.tar.bz2 linux-a73f0425f44ba087751d8e0fa5738f6cd3adf7b9.zip | |
io_uring: Fix registered ring file refcount leak
commit 12d908116f7efd34f255a482b9afc729d7a5fb78 upstream.
Currently, io_uring_unreg_ringfd() (which cleans up registered rings) is
only called on exit, but __io_uring_free (which frees the tctx in which the
registered ring pointers are stored) is also called on execve (via
begin_new_exec -> io_uring_task_cancel -> __io_uring_cancel ->
io_uring_cancel_generic -> __io_uring_free).
This means: A process going through execve while having registered rings
will leak references to the rings' `struct file`.
Fix it by zapping registered rings on execve(). This is implemented by
moving the io_uring_unreg_ringfd() from io_uring_files_cancel() into its
callee __io_uring_cancel(), which is called from io_uring_task_cancel() on
execve.
This could probably be exploited *on 32-bit kernels* by leaking 2^32
references to the same ring, because the file refcount is stored in a
pointer-sized field and get_file() doesn't have protection against
refcount overflow, just a WARN_ONCE(); but on 64-bit it should have no
impact beyond a memory leak.
Cc: stable@vger.kernel.org
Fixes: e7a6c00dc77a ("io_uring: add support for registering ring file descriptors")
Signed-off-by: Jann Horn <jannh@google.com>
Link: https://lore.kernel.org/r/20241218-uring-reg-ring-cleanup-v1-1-8f63e999045b@google.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'io_uring')
| -rw-r--r-- | io_uring/io_uring.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index 70dd6a5b9647..cc31643b7069 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -3431,6 +3431,7 @@ end_wait: void __io_uring_cancel(bool cancel_all) { + io_uring_unreg_ringfd(); io_uring_cancel_generic(cancel_all, NULL); } |