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e787ec1376
The inline assembly in kernel_execve() uses r8 and r9. Since this code sequence does not return, it usually doesn't matter if the register clobber list is accurate. However, I saw a case where a particular version of gcc used r8 as an intermediate for the value eventually passed to r9. Because r8 is used in the inline assembly, and not mentioned in the clobber list, r9 was set to an incorrect value. This resulted in a kernel panic on execution of the first user-space program in the system. r9 is used in ret_to_user as the thread_info pointer, and if it's wrong, bad things happen. Cc: <stable@vger.kernel.org> Signed-off-by: Tim Bird <tim.bird@am.sony.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
134 lines
3.4 KiB
C
134 lines
3.4 KiB
C
/*
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* linux/arch/arm/kernel/sys_arm.c
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*
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* Copyright (C) People who wrote linux/arch/i386/kernel/sys_i386.c
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* Copyright (C) 1995, 1996 Russell King.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This file contains various random system calls that
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* have a non-standard calling sequence on the Linux/arm
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* platform.
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*/
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#include <linux/export.h>
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#include <linux/errno.h>
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#include <linux/sched.h>
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#include <linux/mm.h>
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#include <linux/sem.h>
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#include <linux/msg.h>
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#include <linux/shm.h>
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#include <linux/stat.h>
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#include <linux/syscalls.h>
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#include <linux/mman.h>
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#include <linux/fs.h>
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#include <linux/file.h>
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#include <linux/ipc.h>
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#include <linux/uaccess.h>
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#include <linux/slab.h>
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/* Fork a new task - this creates a new program thread.
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* This is called indirectly via a small wrapper
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*/
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asmlinkage int sys_fork(struct pt_regs *regs)
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{
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#ifdef CONFIG_MMU
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return do_fork(SIGCHLD, regs->ARM_sp, regs, 0, NULL, NULL);
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#else
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/* can not support in nommu mode */
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return(-EINVAL);
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#endif
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}
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/* Clone a task - this clones the calling program thread.
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* This is called indirectly via a small wrapper
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*/
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asmlinkage int sys_clone(unsigned long clone_flags, unsigned long newsp,
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int __user *parent_tidptr, int tls_val,
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int __user *child_tidptr, struct pt_regs *regs)
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{
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if (!newsp)
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newsp = regs->ARM_sp;
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return do_fork(clone_flags, newsp, regs, 0, parent_tidptr, child_tidptr);
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}
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asmlinkage int sys_vfork(struct pt_regs *regs)
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{
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return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->ARM_sp, regs, 0, NULL, NULL);
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}
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/* sys_execve() executes a new program.
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* This is called indirectly via a small wrapper
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*/
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asmlinkage int sys_execve(const char __user *filenamei,
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const char __user *const __user *argv,
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const char __user *const __user *envp, struct pt_regs *regs)
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{
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int error;
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char * filename;
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filename = getname(filenamei);
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error = PTR_ERR(filename);
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if (IS_ERR(filename))
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goto out;
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error = do_execve(filename, argv, envp, regs);
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putname(filename);
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out:
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return error;
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}
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int kernel_execve(const char *filename,
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const char *const argv[],
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const char *const envp[])
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{
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struct pt_regs regs;
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int ret;
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memset(®s, 0, sizeof(struct pt_regs));
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ret = do_execve(filename,
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(const char __user *const __user *)argv,
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(const char __user *const __user *)envp, ®s);
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if (ret < 0)
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goto out;
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/*
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* Save argc to the register structure for userspace.
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*/
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regs.ARM_r0 = ret;
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/*
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* We were successful. We won't be returning to our caller, but
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* instead to user space by manipulating the kernel stack.
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*/
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asm( "add r0, %0, %1\n\t"
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"mov r1, %2\n\t"
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"mov r2, %3\n\t"
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"bl memmove\n\t" /* copy regs to top of stack */
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"mov r8, #0\n\t" /* not a syscall */
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"mov r9, %0\n\t" /* thread structure */
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"mov sp, r0\n\t" /* reposition stack pointer */
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"b ret_to_user"
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:
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: "r" (current_thread_info()),
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"Ir" (THREAD_START_SP - sizeof(regs)),
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"r" (®s),
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"Ir" (sizeof(regs))
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: "r0", "r1", "r2", "r3", "r8", "r9", "ip", "lr", "memory");
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out:
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return ret;
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}
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EXPORT_SYMBOL(kernel_execve);
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/*
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* Since loff_t is a 64 bit type we avoid a lot of ABI hassle
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* with a different argument ordering.
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*/
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asmlinkage long sys_arm_fadvise64_64(int fd, int advice,
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loff_t offset, loff_t len)
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{
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return sys_fadvise64_64(fd, offset, len, advice);
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}
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