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authorSergei Trofimovich <slyfox@gentoo.org>2021-04-09 13:27:32 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2021-04-14 08:22:32 +0200
commitd3d4de0fc05dc820ccf4ac6bad179287248146a1 (patch)
tree68ce49eb0b2e7d13a6f89d456d43d2e88c43fbe2 /arch/ia64
parent426853f87e34c9945a655e8997d2f551b12ceb76 (diff)
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ia64: fix user_stack_pointer() for ptrace()
commit 7ad1e366167837daeb93d0bacb57dee820b0b898 upstream. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/ia64')
-rw-r--r--arch/ia64/include/asm/ptrace.h8
1 files changed, 1 insertions, 7 deletions
diff --git a/arch/ia64/include/asm/ptrace.h b/arch/ia64/include/asm/ptrace.h
index 7ff574d56429..f31e07fc936d 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)