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| author | Sergei Trofimovich <slyfox@gentoo.org> | 2021-04-09 22:27:32 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-04-09 23:54:23 +0200 |
| commit | 7ad1e366167837daeb93d0bacb57dee820b0b898 (patch) | |
| tree | de3fd1892ce5e6e033661d7bdac856c8a71bffa1 /arch/ia64 | |
| parent | ocfs2: fix deadlock between setattr and dio_end_io_write (diff) | |
| download | linux-7ad1e366167837daeb93d0bacb57dee820b0b898.tar.xz linux-7ad1e366167837daeb93d0bacb57dee820b0b898.zip | |
ia64: fix user_stack_pointer() for ptrace()
ia64 has two stacks:
- memory stack (or stack), pointed at by by r12
- register backing store (register stack), pointed at by
ar.bsp/ar.bspstore with complications around dirty
register frame on CPU.
In [1] Dmitry noticed that PTRACE_GET_SYSCALL_INFO returns the register
stack instead memory stack.
The bug comes from the fact that user_stack_pointer() and
current_user_stack_pointer() don't return the same register:
ulong user_stack_pointer(struct pt_regs *regs) { return regs->ar_bspstore; }
#define current_user_stack_pointer() (current_pt_regs()->r12)
The change gets both back in sync.
I think ptrace(PTRACE_GET_SYSCALL_INFO) is the only affected user by
this bug on ia64.
The change fixes 'rt_sigreturn.gen.test' strace test where it was
observed initially.
Link: https://bugs.gentoo.org/769614 [1]
Link: https://lkml.kernel.org/r/20210331084447.2561532-1-slyfox@gentoo.org
Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
Reported-by: Dmitry V. Levin <ldv@altlinux.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/ia64')
| -rw-r--r-- | arch/ia64/include/asm/ptrace.h | 8 |
1 files changed, 1 insertions, 7 deletions
diff --git a/arch/ia64/include/asm/ptrace.h b/arch/ia64/include/asm/ptrace.h index b3aa46090101..08179135905c 100644 --- a/arch/ia64/include/asm/ptrace.h +++ b/arch/ia64/include/asm/ptrace.h @@ -54,8 +54,7 @@ static inline unsigned long user_stack_pointer(struct pt_regs *regs) { - /* FIXME: should this be bspstore + nr_dirty regs? */ - return regs->ar_bspstore; + return regs->r12; } static inline int is_syscall_success(struct pt_regs *regs) @@ -79,11 +78,6 @@ static inline long regs_return_value(struct pt_regs *regs) unsigned long __ip = instruction_pointer(regs); \ (__ip & ~3UL) + ((__ip & 3UL) << 2); \ }) -/* - * Why not default? Because user_stack_pointer() on ia64 gives register - * stack backing store instead... - */ -#define current_user_stack_pointer() (current_pt_regs()->r12) /* given a pointer to a task_struct, return the user's pt_regs */ # define task_pt_regs(t) (((struct pt_regs *) ((char *) (t) + IA64_STK_OFFSET)) - 1) |