From 2cbfdf4df58330f6cb493500387427dae1c5551d Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Fri, 2 Nov 2018 17:16:51 +0000 Subject: iov_iter: Fix 9p virtio breakage When switching to the new iovec accessors, a negation got subtly dropped, leading to 9p being remarkably broken (here with kvmtool): [ 7.430941] VFS: Mounted root (9p filesystem) on device 0:15. [ 7.432080] devtmpfs: mounted [ 7.432717] Freeing unused kernel memory: 1344K [ 7.433658] Run /virt/init as init process Warning: unable to translate guest address 0x7e00902ff000 to host Warning: unable to translate guest address 0x7e00902fefc0 to host Warning: unable to translate guest address 0x7e00902ff000 to host Warning: unable to translate guest address 0x7e008febef80 to host Warning: unable to translate guest address 0x7e008febf000 to host Warning: unable to translate guest address 0x7e008febef00 to host Warning: unable to translate guest address 0x7e008febf000 to host [ 7.436376] Kernel panic - not syncing: Requested init /virt/init failed (error -8). [ 7.437554] CPU: 29 PID: 1 Comm: swapper/0 Not tainted 4.19.0-rc8-02267-g00e23707442a #291 [ 7.439006] Hardware name: linux,dummy-virt (DT) [ 7.439902] Call trace: [ 7.440387] dump_backtrace+0x0/0x148 [ 7.441104] show_stack+0x14/0x20 [ 7.441768] dump_stack+0x90/0xb4 [ 7.442425] panic+0x120/0x27c [ 7.443036] kernel_init+0xa4/0x100 [ 7.443725] ret_from_fork+0x10/0x18 [ 7.444444] SMP: stopping secondary CPUs [ 7.445391] Kernel Offset: disabled [ 7.446169] CPU features: 0x0,23000438 [ 7.446974] Memory Limit: none [ 7.447645] ---[ end Kernel panic - not syncing: Requested init /virt/init failed (error -8). ]--- Restoring the missing "!" brings the guest back to life. Fixes: 00e23707442a ("iov_iter: Use accessor function") Reported-by: Will Deacon Signed-off-by: Marc Zyngier Signed-off-by: Al Viro --- net/9p/trans_virtio.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/9p') diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c index 4d7d2070e9c8..ce94e5668ac2 100644 --- a/net/9p/trans_virtio.c +++ b/net/9p/trans_virtio.c @@ -322,7 +322,7 @@ static int p9_get_mapped_pages(struct virtio_chan *chan, if (!iov_iter_count(data)) return 0; - if (iov_iter_is_kvec(data)) { + if (!iov_iter_is_kvec(data)) { int n; /* * We allow only p9_max_pages pinned. We wait for the -- cgit v1.2.3-59-g8ed1b