Re: [PATCH rc v2] RDMA/cma: Do not change route.addr.src_addr outside state checks

[Jason Gunthorpe <jgg@nvidia.com>]

On Wed, Feb 23, 2022 at 11:23:57AM -0400, Jason Gunthorpe wrote:
> If the state is not idle then resolve_prepare_src() should immediately
> fail and no change to global state should happen. However, it
> unconditionally overwrites the src_addr trying to build a temporary any
> address.
> 
> For instance if the state is already RDMA_CM_LISTEN then this will corrupt
> the src_addr and would cause the test in cma_cancel_operation():
> 
>            if (cma_any_addr(cma_src_addr(id_priv)) && !id_priv->cma_dev)
> 
> Which would manifest as this trace from syzkaller:
> 
>   BUG: KASAN: use-after-free in __list_add_valid+0x93/0xa0 lib/list_debug.c:26
>   Read of size 8 at addr ffff8881546491e0 by task syz-executor.1/32204
> 
>   CPU: 1 PID: 32204 Comm: syz-executor.1 Not tainted 5.12.0-rc8-syzkaller #0
>   Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
>   Call Trace:
>    __dump_stack lib/dump_stack.c:79 [inline]
>    dump_stack+0x141/0x1d7 lib/dump_stack.c:120
>    print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:232
>    __kasan_report mm/kasan/report.c:399 [inline]
>    kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:416
>    __list_add_valid+0x93/0xa0 lib/list_debug.c:26
>    __list_add include/linux/list.h:67 [inline]
>    list_add_tail include/linux/list.h:100 [inline]
>    cma_listen_on_all drivers/infiniband/core/cma.c:2557 [inline]
>    rdma_listen+0x787/0xe00 drivers/infiniband/core/cma.c:3751
>    ucma_listen+0x16a/0x210 drivers/infiniband/core/ucma.c:1102
>    ucma_write+0x259/0x350 drivers/infiniband/core/ucma.c:1732
>    vfs_write+0x28e/0xa30 fs/read_write.c:603
>    ksys_write+0x1ee/0x250 fs/read_write.c:658
>    do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
>    entry_SYSCALL_64_after_hwframe+0x44/0xae
> 
> This is indicating that an rdma_id_private was destroyed without doing
> cma_cancel_listens().
> 
> Instead of trying to re-use the src_addr memory to indirectly create an
> any address derived from the dst build one explicitly on the stack and
> bind to that as any other normal flow would do. rdma_bind_addr() will copy
> it over the src_addr once it knows the state is valid.
> 
> This is similar to commit bc0bdc5afaa7 ("RDMA/cma: Do not change
> route.addr.src_addr.ss_family")
> 
> Cc: stable@vger.kernel.org
> Fixes: 732d41c545bb ("RDMA/cma: Make the locking for automatic state transition more clear")
> Reported-by: syzbot+c94a3675a626f6333d74@syzkaller.appspotmail.com
> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
> Reviewed-by: Leon Romanovsky <leonro@nvidia.com>

Applied to for-rc

Jason