6.1-stable review patch. If anyone has any objections, please let me know.
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From: Dominik Grzegorzek dominik.grzegorzek@oracle.com
commit d6ebcde6d4ecf34f8495fb30516645db3aea8993 upstream.
A recent patch that addressed a UAF introduced a reference count leak: the parallel_data refcount is incremented unconditionally, regardless of the return value of queue_work(). If the work item is already queued, the incremented refcount is never decremented.
Fix this by checking the return value of queue_work() and decrementing the refcount when necessary.
Resolves:
Unreferenced object 0xffff9d9f421e3d80 (size 192): comm "cryptomgr_probe", pid 157, jiffies 4294694003 hex dump (first 32 bytes): 80 8b cf 41 9f 9d ff ff b8 97 e0 89 ff ff ff ff ...A............ d0 97 e0 89 ff ff ff ff 19 00 00 00 1f 88 23 00 ..............#. backtrace (crc 838fb36): __kmalloc_cache_noprof+0x284/0x320 padata_alloc_pd+0x20/0x1e0 padata_alloc_shell+0x3b/0xa0 0xffffffffc040a54d cryptomgr_probe+0x43/0xc0 kthread+0xf6/0x1f0 ret_from_fork+0x2f/0x50 ret_from_fork_asm+0x1a/0x30
Fixes: dd7d37ccf6b1 ("padata: avoid UAF for reorder_work") Cc: stable@vger.kernel.org Signed-off-by: Dominik Grzegorzek dominik.grzegorzek@oracle.com Signed-off-by: Herbert Xu herbert@gondor.apana.org.au Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/padata.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/kernel/padata.c +++ b/kernel/padata.c @@ -350,7 +350,8 @@ static void padata_reorder(struct parall * To avoid UAF issue, add pd ref here, and put pd ref after reorder_work finish. */ padata_get_pd(pd); - queue_work(pinst->serial_wq, &pd->reorder_work); + if (!queue_work(pinst->serial_wq, &pd->reorder_work)) + padata_put_pd(pd); } }