da8d0fc4fa
if new shared mappings of files/devices/shared memory can be made between the time a robust mutex is unlocked and its subsequent removal from the pending slot in the robustlist header, the kernel can inadvertently corrupt data in the newly-mapped pages when the process terminates. i am fixing the bug by using the same global vm lock mechanism that was used to fix the race condition with unmapping barriers after pthread_barrier_wait returns.
22 lines
428 B
C
22 lines
428 B
C
#include "pthread_impl.h"
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static int vmlock[2];
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void __vm_lock(int inc)
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{
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for (;;) {
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int v = vmlock[0];
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if (inc*v < 0) __wait(vmlock, vmlock+1, v, 1);
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else if (a_cas(vmlock, v, v+inc)==v) break;
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}
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}
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void __vm_unlock(void)
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{
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int inc = vmlock[0]>0 ? -1 : 1;
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if (a_fetch_add(vmlock, inc)==-inc && vmlock[1])
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__wake(vmlock, -1, 1);
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}
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weak_alias(__vm_lock, __vm_lock_impl);
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weak_alias(__vm_unlock, __vm_unlock_impl);
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