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From: Andrew Morton <akpm@linux-foundation.org>
To: akpm@linux-foundation.org, ldv@altlinux.org, linux-mm@kvack.org,
	mm-commits@vger.kernel.org, oleg@redhat.com, slyfox@gentoo.org,
	stable@vger.kernel.org, torvalds@linux-foundation.org
Subject: [patch 11/16] ia64: fix user_stack_pointer() for ptrace()
Date: Fri, 09 Apr 2021 13:27:32 -0700	[thread overview]
Message-ID: <20210409202732.BFWhCou9S%akpm@linux-foundation.org> (raw)
In-Reply-To: <20210409132633.6855fc8fea1b3905ea1bb4be@linux-foundation.org>

From: Sergei Trofimovich <slyfox@gentoo.org>
Subject: 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
  ar.bsp/ar.bspstore with complications around dirty
  register frame on CPU.

In https://bugs.gentoo.org/769614 Dmitry noticed that
PTRACE_GET_SYSCALL_INFO returns 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://lkml.kernel.org/r/20210331084447.2561532-1-slyfox@gentoo.org
Link: https://bugs.gentoo.org/769614
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>
---

 arch/ia64/include/asm/ptrace.h |    8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

--- a/arch/ia64/include/asm/ptrace.h~ia64-fix-user_stack_pointer-for-ptrace
+++ a/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(str
 	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)
_

  parent reply	other threads:[~2021-04-09 20:27 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-09 20:26 incoming Andrew Morton
2021-04-09 20:27 ` [patch 01/16] MAINTAINERS: update CZ.NIC's Turris information Andrew Morton
2021-04-09 20:27 ` [patch 02/16] treewide: change my e-mail address, fix my name Andrew Morton
2021-04-09 20:27 ` [patch 03/16] mailmap: update email address for Jordan Crouse Andrew Morton
2021-04-09 20:27 ` [patch 04/16] .mailmap: fix old email addresses Andrew Morton
2021-04-09 20:27 ` [patch 05/16] kasan: fix hwasan build for gcc Andrew Morton
2021-04-09 20:39   ` Andrey Konovalov
2021-04-09 20:58     ` Andrew Morton
2021-04-12  9:56       ` Marco Elver
2021-04-12 12:54         ` Andrey Konovalov
2021-04-09 21:55     ` Linus Torvalds
2021-04-09 20:27 ` [patch 06/16] kasan: remove redundant config option Andrew Morton
2021-04-09 20:27 ` [patch 07/16] mm/gup: check page posion status for coredump Andrew Morton
2021-04-09 20:27 ` [patch 08/16] nds32: flush_dcache_page: use page_mapping_file to avoid races with swapoff Andrew Morton
2021-04-09 20:27 ` [patch 09/16] gcov: re-fix clang-11+ support Andrew Morton
2021-04-09 20:27 ` [patch 10/16] ocfs2: fix deadlock between setattr and dio_end_io_write Andrew Morton
2021-04-09 20:27 ` Andrew Morton [this message]
2021-04-09 20:27 ` [patch 12/16] fs: direct-io: fix missing sdio->boundary Andrew Morton
2021-04-09 20:27 ` [patch 13/16] kasan: fix conflict with page poisoning Andrew Morton
2021-04-09 20:27 ` [patch 14/16] lib/test_kasan_module.c: suppress unused var warning Andrew Morton
2021-04-09 20:27 ` [patch 15/16] kfence, x86: fix preemptible warning on KPTI-enabled systems Andrew Morton
2021-04-09 20:27 ` [patch 16/16] lib: fix kconfig dependency on ARCH_WANT_FRAME_POINTERS Andrew Morton

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