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pkey state is now preserved on fork for Linux 5.0+

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This patch is going to be backported to stable kernels, so the check
could be expanded to allow recent enough stable kernel branches.
This commit is contained in:
Daniel Micay 2019-03-20 10:55:29 -04:00
parent c9df70d934
commit 4a000d96e2
1 changed files with 17 additions and 4 deletions
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21
h_malloc.c
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@ -8,6 +8,7 @@
#include <malloc.h>
#include <pthread.h>
#include <sys/mman.h>
#include <sys/utsname.h>
#include <unistd.h>
#include "third_party/libdivide.h"
@ -66,6 +67,7 @@ static union {
struct region_metadata *regions[2];
#ifdef USE_PKEY
int metadata_pkey;
bool pkey_state_preserved_on_fork;
#endif
};
char padding[PAGE_SIZE];
@ -914,10 +916,12 @@ static void post_fork_child(void) {
thread_unseal_metadata();
#ifdef USE_PKEY
// disable sealing to work around kernel bug causing fork to lose the pkey setup
memory_protect_rw(&ro, sizeof(ro));
ro.metadata_pkey = -1;
memory_protect_ro(&ro, sizeof(ro));
if (!ro.pkey_state_preserved_on_fork) {
// disable sealing to work around kernel bug causing fork to lose the pkey setup
memory_protect_rw(&ro, sizeof(ro));
ro.metadata_pkey = -1;
memory_protect_ro(&ro, sizeof(ro));
}
#endif
mutex_init(&ro.region_allocator->lock);
@ -952,6 +956,15 @@ COLD static void init_slow_path(void) {
#ifdef USE_PKEY
ro.metadata_pkey = pkey_alloc(0, 0);
// pkey state is not preserved on fork before Linux 5.0 unless the patch was backported
struct utsname uts;
if (uname(&uts) == 0) {
unsigned long version = strtoul(uts.release, NULL, 10);
if (version >= 5) {
ro.pkey_state_preserved_on_fork = true;
}
}
#endif
if (sysconf(_SC_PAGESIZE) != PAGE_SIZE) {