diff options
| author | Alexander Bulekov <alxndr@bu.edu> | 2023-05-01 10:19:56 -0400 |
|---|---|---|
| committer | Thomas Huth <thuth@redhat.com> | 2023-05-02 10:03:26 +0200 |
| commit | 7915bd06f25e1803778081161bf6fa10c42dc7cd (patch) | |
| tree | 72dc066a0c4d87dc647fe03b78426bc8e21de136 /util | |
| parent | b08dc0f1b7b7b3be27ed3ffd72deeb02a1f669e7 (diff) | |
async: avoid use-after-free on re-entrancy guard
A BH callback can free the BH, causing a use-after-free in aio_bh_call.
Fix that by keeping a local copy of the re-entrancy guard pointer.
Buglink: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=58513
Fixes: 9c86c97f12 ("async: Add an optional reentrancy guard to the BH API")
Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
Message-Id: <20230501141956.3444868-1-alxndr@bu.edu>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Diffstat (limited to 'util')
| -rw-r--r-- | util/async.c | 14 |
1 files changed, 8 insertions, 6 deletions
diff --git a/util/async.c b/util/async.c index 9df7674b4e..055070ffbd 100644 --- a/util/async.c +++ b/util/async.c @@ -156,18 +156,20 @@ void aio_bh_call(QEMUBH *bh) { bool last_engaged_in_io = false; - if (bh->reentrancy_guard) { - last_engaged_in_io = bh->reentrancy_guard->engaged_in_io; - if (bh->reentrancy_guard->engaged_in_io) { + /* Make a copy of the guard-pointer as cb may free the bh */ + MemReentrancyGuard *reentrancy_guard = bh->reentrancy_guard; + if (reentrancy_guard) { + last_engaged_in_io = reentrancy_guard->engaged_in_io; + if (reentrancy_guard->engaged_in_io) { trace_reentrant_aio(bh->ctx, bh->name); } - bh->reentrancy_guard->engaged_in_io = true; + reentrancy_guard->engaged_in_io = true; } bh->cb(bh->opaque); - if (bh->reentrancy_guard) { - bh->reentrancy_guard->engaged_in_io = last_engaged_in_io; + if (reentrancy_guard) { + reentrancy_guard->engaged_in_io = last_engaged_in_io; } } |