The patch titled
Subject: proc: fix PIE proc-empty-vm, proc-pid-vm tests
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
proc-fix-pie-proc-empty-vm-proc-pid-vm-tests.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/proc-fix-pie-proc-empty-vm-proc-pid-vm-tests.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Subject: proc: fix PIE proc-empty-vm, proc-pid-vm tests
Date: Fri, 6 Jan 2023 22:30:14 +0300
vsyscall detection code uses direct call to the beginning of
the vsyscall page:
asm ("call %P0" :: "i" (0xffffffffff600000))
It generates "call rel32" instruction but it is not relocated if binary
is PIE, so binary segfaults into random userspace address and vsyscall
page status is detected incorrectly.
Do more direct:
asm ("call *%rax")
which doesn't do need any relocaltions.
Mark g_vsyscall as volatile for a good measure, I didn't find instruction
setting it to 0. Now the code is obviously correct:
xor eax, eax
mov rdi, rbp
mov rsi, rbp
mov DWORD PTR [rip+0x2d15], eax # g_vsyscall = 0
mov rax, 0xffffffffff600000
call rax
mov DWORD PTR [rip+0x2d02], 1 # g_vsyscall = 1
mov eax, DWORD PTR ds:0xffffffffff600000
mov DWORD PTR [rip+0x2cf1], 2 # g_vsyscall = 2
mov edi, [rip+0x2ceb] # exit(g_vsyscall)
call exit
Note: fixed proc-empty-vm test oopses 5.19.0-28-generic kernel
but this is separate story.
Link: https://lkml.kernel.org/r/Y7h2xvzKLg36DSq8@p183
Fixes: 5bc73bb3451b9 ("proc: test how it holds up with mapping'less process")
Signed-off-by: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Reported-by: Mirsad Goran Todorovac <mirsad.todorovac@xxxxxxxxxxxx>
Tested-by: Mirsad Goran Todorovac <mirsad.todorovac@xxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
tools/testing/selftests/proc/proc-empty-vm.c | 12 +++++++-----
tools/testing/selftests/proc/proc-pid-vm.c | 9 +++++----
2 files changed, 12 insertions(+), 9 deletions(-)
--- a/tools/testing/selftests/proc/proc-empty-vm.c~proc-fix-pie-proc-empty-vm-proc-pid-vm-tests
+++ a/tools/testing/selftests/proc/proc-empty-vm.c
@@ -25,6 +25,7 @@
#undef NDEBUG
#include <assert.h>
#include <errno.h>
+#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
@@ -41,7 +42,7 @@
* 1: vsyscall VMA is --xp vsyscall=xonly
* 2: vsyscall VMA is r-xp vsyscall=emulate
*/
-static int g_vsyscall;
+static volatile int g_vsyscall;
static const char *g_proc_pid_maps_vsyscall;
static const char *g_proc_pid_smaps_vsyscall;
@@ -147,11 +148,12 @@ static void vsyscall(void)
g_vsyscall = 0;
/* gettimeofday(NULL, NULL); */
+ uint64_t rax = 0xffffffffff600000;
asm volatile (
- "call %P0"
- :
- : "i" (0xffffffffff600000), "D" (NULL), "S" (NULL)
- : "rax", "rcx", "r11"
+ "call *%[rax]"
+ : [rax] "+a" (rax)
+ : "D" (NULL), "S" (NULL)
+ : "rcx", "r11"
);
g_vsyscall = 1;
--- a/tools/testing/selftests/proc/proc-pid-vm.c~proc-fix-pie-proc-empty-vm-proc-pid-vm-tests
+++ a/tools/testing/selftests/proc/proc-pid-vm.c
@@ -257,11 +257,12 @@ static void vsyscall(void)
g_vsyscall = 0;
/* gettimeofday(NULL, NULL); */
+ uint64_t rax = 0xffffffffff600000;
asm volatile (
- "call %P0"
- :
- : "i" (0xffffffffff600000), "D" (NULL), "S" (NULL)
- : "rax", "rcx", "r11"
+ "call *%[rax]"
+ : [rax] "+a" (rax)
+ : "D" (NULL), "S" (NULL)
+ : "rcx", "r11"
);
g_vsyscall = 1;
_
Patches currently in -mm which might be from adobriyan@xxxxxxxxx are
proc-fix-pie-proc-empty-vm-proc-pid-vm-tests.patch
proc-mark-proc-cmdline-as-permanent.patch
