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| author | Vasily Gorbik <gor@linux.ibm.com> | 2018-09-14 18:29:39 +0300 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2018-09-20 14:20:29 +0300 |
| commit | d1befa65823e9c6d013883b8a41d081ec338c489 (patch) | |
| tree | e41d581c2cd188884a016bd9f689eb57ae60f1f5 /arch/s390/kernel/vdso.c | |
| parent | 1c472d46283263497adccd7a0bec64ee2f9c09e5 (diff) | |
| download | linux-d1befa65823e9c6d013883b8a41d081ec338c489.tar.xz | |
s390/vdso: avoid 64-bit vdso mapping for compat tasks
vdso_fault used is_compat_task function (on s390 it tests "current"
thread_info flags) to distinguish compat tasks and map 31-bit vdso
pages. But "current" task might not correspond to mm context.
When 31-bit compat inferior is executed under gdb, gdb does
PTRACE_PEEKTEXT on vdso page, causing vdso_fault with "current" being
64-bit gdb process. So, 31-bit inferior ends up with 64-bit vdso mapped.
To avoid this problem a new compat_mm flag has been introduced into
mm context. This flag is used in vdso_fault and vdso_mremap instead
of is_compat_task.
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/kernel/vdso.c')
| -rw-r--r-- | arch/s390/kernel/vdso.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/arch/s390/kernel/vdso.c b/arch/s390/kernel/vdso.c index 3031cc6dd0ab..ec31b48a42a5 100644 --- a/arch/s390/kernel/vdso.c +++ b/arch/s390/kernel/vdso.c @@ -56,7 +56,7 @@ static vm_fault_t vdso_fault(const struct vm_special_mapping *sm, vdso_pagelist = vdso64_pagelist; vdso_pages = vdso64_pages; #ifdef CONFIG_COMPAT - if (is_compat_task()) { + if (vma->vm_mm->context.compat_mm) { vdso_pagelist = vdso32_pagelist; vdso_pages = vdso32_pages; } @@ -77,7 +77,7 @@ static int vdso_mremap(const struct vm_special_mapping *sm, vdso_pages = vdso64_pages; #ifdef CONFIG_COMPAT - if (is_compat_task()) + if (vma->vm_mm->context.compat_mm) vdso_pages = vdso32_pages; #endif @@ -224,8 +224,10 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) vdso_pages = vdso64_pages; #ifdef CONFIG_COMPAT - if (is_compat_task()) + if (is_compat_task()) { vdso_pages = vdso32_pages; + mm->context.compat_mm = 1; + } #endif /* * vDSO has a problem and was disabled, just don't "enable" it for |