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authorAndrei Vagin <avagin@gmail.com>2020-09-25 14:18:19 -0700
committerAndrei Vagin <avagin@gmail.com>2020-10-02 13:16:58 -0700
commitde85b045d42f503d6463a86145d797b8deb22604 (patch)
treef93b199c100e63fc8aef44eab0bd07349afee16f /pkg/linewriter/BUILD
parent0cea6472188e056673fd0ab8ff06a25dbe44ca52 (diff)
kvm/x86: handle a case when interrupts are enabled in the kernel space
Before we thought that interrupts are always disabled in the kernel space, but here is a case when goruntime switches on a goroutine which has been saved in the host mode. On restore, the popf instruction is used to restore flags and this means that all flags what the goroutine has in the host mode will be restored in the kernel mode. And in the host mode, interrupts are always enabled. The long story short, we can't use the IF flag for determine whether a tasks is running in user or kernel mode. This patch reworks the code so that in userspace, the first bit of the IOPL flag will be always set. This doesn't give any new privilidges for a task because CPL in userspace is always 3. But then we can use this flag to distinguish user and kernel modes. The IOPL flag is never set in the kernel and host modes. Reported-by: syzbot+5036b325a8eb15c030cf@syzkaller.appspotmail.com Reported-by: syzbot+034d580e89ad67b8dc75@syzkaller.appspotmail.com Signed-off-by: Andrei Vagin <avagin@gmail.com>
Diffstat (limited to 'pkg/linewriter/BUILD')
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