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[wasm] Disable PKU on Linux kernels <5.13

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Those versions are broken, and sporadically reset the PKRU register on
context switches (observed on ChromeOS only). This was fixed by this
patch:
https://lore.kernel.org/all/20210623121456.399107624@linutronix.de/

Thus we detect the running kernel version (once per process), and
disable PKU if we detect a potentially broken kernel version.

R=jkummerow@chromium.org

Bug: v8:11974
Change-Id: Ib5158b4cf51d5c2811678b1b7dcc1494bc0ff46a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3417440
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78857}
This commit is contained in:
Clemens Backes 2022-01-28 20:32:04 +01:00 committed by V8 LUCI CQ
parent a38f8d5c72
commit b92fdea673
1 changed files with 13 additions and 1 deletions
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14
src/wasm/memory-protection-key.cc
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@ -5,7 +5,8 @@
#include "src/wasm/memory-protection-key.h" #include "src/wasm/memory-protection-key.h"
#if defined(V8_OS_LINUX) && defined(V8_HOST_ARCH_X64) #if defined(V8_OS_LINUX) && defined(V8_HOST_ARCH_X64)
#include <sys/mman.h> // For {mprotect()} protection macros. #include <sys/mman.h> // For {mprotect()} protection macros.
#include <sys/utsname.h> // For {uname()}.
#undef MAP_TYPE // Conflicts with MAP_TYPE in Torque-generated instance-types.h #undef MAP_TYPE // Conflicts with MAP_TYPE in Torque-generated instance-types.h
#endif #endif
@ -65,6 +66,17 @@ void InitializeMemoryProtectionKeySupport() {
// Flip {pkey_initialized} (in debug mode) and check the new value. // Flip {pkey_initialized} (in debug mode) and check the new value.
DCHECK_EQ(true, pkey_initialized = !pkey_initialized); DCHECK_EQ(true, pkey_initialized = !pkey_initialized);
#if defined(V8_OS_LINUX) && defined(V8_HOST_ARCH_X64) #if defined(V8_OS_LINUX) && defined(V8_HOST_ARCH_X64)
// PKU is broken on Linux kernels before 5.13 (see
// https://lore.kernel.org/all/20210623121456.399107624@linutronix.de/).
// Thus check the kernel version we are running on, and bail out if it's
// not at least 5.13.
struct utsname uname_buffer;
CHECK_EQ(0, uname(&uname_buffer));
int major, minor;
// Conservatively return if the release does not match the format we expect.
if (sscanf(uname_buffer.release, "%d.%d.", &major, &minor) != 2) return;
if (major < 5 || (major == 5 && minor < 13)) return;
// Try to to find the pkey functions in glibc. // Try to to find the pkey functions in glibc.
void* pkey_alloc_ptr = dlsym(RTLD_DEFAULT, "pkey_alloc"); void* pkey_alloc_ptr = dlsym(RTLD_DEFAULT, "pkey_alloc");
if (!pkey_alloc_ptr) return; if (!pkey_alloc_ptr) return;