Patch "arm64: ptrace: change fs when passing kernel pointer to regset code" has been added to the 3.15-stable tree

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



This is a note to let you know that I've just added the patch titled

    arm64: ptrace: change fs when passing kernel pointer to regset code

to the 3.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     arm64-ptrace-change-fs-when-passing-kernel-pointer-to-regset-code.patch
and it can be found in the queue-3.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From c168870704bcde6bb63d05f7882b620dd3985a46 Mon Sep 17 00:00:00 2001
From: Will Deacon <will.deacon@xxxxxxx>
Date: Mon, 2 Jun 2014 11:47:23 +0100
Subject: arm64: ptrace: change fs when passing kernel pointer to regset code

From: Will Deacon <will.deacon@xxxxxxx>

commit c168870704bcde6bb63d05f7882b620dd3985a46 upstream.

Our compat PTRACE_POKEUSR implementation simply passes the user data to
regset_copy_from_user after some simple range checking. Unfortunately,
the data in question has already been copied to the kernel stack by this
point, so the subsequent access_ok check fails and the ptrace request
returns -EFAULT. This causes problems tracing fork() with older versions
of strace.

This patch briefly changes the fs to KERNEL_DS, so that the access_ok
check passes even with a kernel address.

Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/arm64/kernel/ptrace.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -821,6 +821,7 @@ static int compat_ptrace_write_user(stru
 				    compat_ulong_t val)
 {
 	int ret;
+	mm_segment_t old_fs = get_fs();
 
 	if (off & 3 || off >= COMPAT_USER_SZ)
 		return -EIO;
@@ -828,10 +829,13 @@ static int compat_ptrace_write_user(stru
 	if (off >= sizeof(compat_elf_gregset_t))
 		return 0;
 
+	set_fs(KERNEL_DS);
 	ret = copy_regset_from_user(tsk, &user_aarch32_view,
 				    REGSET_COMPAT_GPR, off,
 				    sizeof(compat_ulong_t),
 				    &val);
+	set_fs(old_fs);
+
 	return ret;
 }
 


Patches currently in stable-queue which might be from will.deacon@xxxxxxx are

queue-3.15/arm64-ptrace-change-fs-when-passing-kernel-pointer-to-regset-code.patch
queue-3.15/arm64-ptrace-fix-empty-registers-set-in-prstatus-of-aarch32-process-core.patch
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Index of Archives]     [Linux Kernel]     [Kernel Development Newbies]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite Hiking]     [Linux Kernel]     [Linux SCSI]