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/selftests-mm-virtual_address_range-avoid-reading-vvar-mappings.patch
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 WeiÃ?schuh <thomas.weissschuh@xxxxxxxxxxxxx>
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-v1-2-3834a2fb47fe@xxxxxxxxxxxxx
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 WeiÃ?schuh <thomas.weissschuh@xxxxxxxxxxxxx>
Reported-by: kernel test robot <oliver.sang@xxxxxxxxx>
Closes: https://lore.kernel.org/oe-lkp/202412271148.2656e485-lkp@xxxxxxxxx
Cc: Dev Jain <dev.jain@xxxxxxx>
Cc: Shuah Khan <shuah@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
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@xxxxxxxxxxxxx are
selftests-mm-virtual_address_range-fix-error-when-commitlimit-1gib.patch
selftests-mm-virtual_address_range-avoid-reading-vvar-mappings.patch
