The patch titled Subject: selftests/mm: virtual_address_range: avoid reading VVAR mappings has been added to the -mm mm-hotfixes-unstable branch. Its filename is selftests-mm-virtual_address_range-avoid-reading-vvar-mappings.patch
This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...
This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------ From: Thomas Wei��schuh thomas.weissschuh@linutronix.de Subject: selftests/mm: virtual_address_range: avoid reading VVAR mappings Date: Tue, 07 Jan 2025 16:14:46 +0100
The virtual_address_range selftest reads from the start of each mapping listed in /proc/self/maps.
However not all mappings are valid to be arbitrarily accessed. For example the vvar data used for virtual clocks on x86 can only be accessed if 1) the kernel configuration enables virtual clocks and 2) the hypervisor provided the data for it, which can only determined by the VDSO code itself.
Since commit e93d2521b27f ("x86/vdso: Split virtual clock pages into dedicated mapping") the virtual clock data was split out into its own mapping, triggering faulting accesses by virtual_address_range.
Skip the various vvar mappings in virtual_address_range to avoid errors.
Link: https://lkml.kernel.org/r/20250107-virtual_address_range-tests-v1-2-3834a2fb... Fixes: e93d2521b27f ("x86/vdso: Split virtual clock pages into dedicated mapping") Fixes: 010409649885 ("selftests/mm: confirm VA exhaustion without reliance on correctness of mmap()") Signed-off-by: Thomas Wei��schuh thomas.weissschuh@linutronix.de Reported-by: kernel test robot oliver.sang@intel.com Closes: https://lore.kernel.org/oe-lkp/202412271148.2656e485-lkp@intel.com Cc: Dev Jain dev.jain@arm.com Cc: Shuah Khan shuah@kernel.org Cc: Thomas Gleixner tglx@linutronix.de Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---
tools/testing/selftests/mm/virtual_address_range.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)
--- a/tools/testing/selftests/mm/virtual_address_range.c~selftests-mm-virtual_address_range-avoid-reading-vvar-mappings +++ a/tools/testing/selftests/mm/virtual_address_range.c @@ -116,10 +116,11 @@ static int validate_complete_va_space(vo
prev_end_addr = 0; while (fgets(line, sizeof(line), file)) { + int path_offset = 0; unsigned long hop;
- if (sscanf(line, "%lx-%lx %s[rwxp-]", - &start_addr, &end_addr, prot) != 3) + if (sscanf(line, "%lx-%lx %4s %*s %*s %*s %n", + &start_addr, &end_addr, prot, &path_offset) != 3) ksft_exit_fail_msg("cannot parse /proc/self/maps\n");
/* end of userspace mappings; ignore vsyscall mapping */ @@ -135,6 +136,10 @@ static int validate_complete_va_space(vo if (prot[0] != 'r') continue;
+ /* Only the VDSO can know if a VVAR mapping is really readable */ + if (path_offset && !strncmp(line + path_offset, "[vvar", 5)) + continue; + /* * Confirm whether MAP_CHUNK_SIZE chunk can be found or not. * If write succeeds, no need to check MAP_CHUNK_SIZE - 1 _
Patches currently in -mm which might be from thomas.weissschuh@linutronix.de are
selftests-mm-virtual_address_range-fix-error-when-commitlimit-1gib.patch selftests-mm-virtual_address_range-avoid-reading-vvar-mappings.patch