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mm: replace access_process_vm() write parameter with gup_flags 

This removes the 'write' argument from access_process_vm() and replaces
it with 'gup_flags' as use of this function previously silently implied
FOLL_FORCE, whereas after this patch callers explicitly pass this flag.

We make this explicit as use of FOLL_FORCE can result in surprising
behaviour (and hence bugs) within the mm subsystem.

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Lorenzo Stoakes 2016-10-13 01:20:20 +01:00 committed by Linus Torvalds
parent 6347e8d5bc
commit f307ab6dce
17 changed files with 84 additions and 54 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
arch/alpha/kernel/ptrace.c
View File

@ -157,14 +157,16 @@ put_reg(struct task_struct *task, unsigned long regno, unsigned long data)
static inline int
read_int(struct task_struct *task, unsigned long addr, int * data)
{
int copied = access_process_vm(task, addr, data, sizeof(int), 0);
int copied = access_process_vm(task, addr, data, sizeof(int),
FOLL_FORCE);
return (copied == sizeof(int)) ? 0 : -EIO;
}
static inline int
write_int(struct task_struct *task, unsigned long addr, int data)
{
int copied = access_process_vm(task, addr, &data, sizeof(int), 1);
int copied = access_process_vm(task, addr, &data, sizeof(int),
FOLL_FORCE | FOLL_WRITE);
return (copied == sizeof(int)) ? 0 : -EIO;
}
@ -281,7 +283,8 @@ long arch_ptrace(struct task_struct *child, long request,
/* When I and D space are separate, these will need to be fixed. */
case PTRACE_PEEKTEXT: /* read word at location addr. */
case PTRACE_PEEKDATA:
copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
copied = access_process_vm(child, addr, &tmp, sizeof(tmp),
FOLL_FORCE);
ret = -EIO;
if (copied != sizeof(tmp))
break;

5
arch/blackfin/kernel/ptrace.c
View File

@ -271,7 +271,7 @@ long arch_ptrace(struct task_struct *child, long request,
case BFIN_MEM_ACCESS_CORE:
case BFIN_MEM_ACCESS_CORE_ONLY:
copied = access_process_vm(child, addr, &tmp,
to_copy, 0);
to_copy, FOLL_FORCE);
if (copied)
break;
@ -324,7 +324,8 @@ long arch_ptrace(struct task_struct *child, long request,
case BFIN_MEM_ACCESS_CORE:
case BFIN_MEM_ACCESS_CORE_ONLY:
copied = access_process_vm(child, addr, &data,
to_copy, 1);
to_copy,
FOLL_FORCE | FOLL_WRITE);
break;
case BFIN_MEM_ACCESS_DMA:
if (safe_dma_memcpy(paddr, &data, to_copy))

4
arch/cris/arch-v32/kernel/ptrace.c
View File

@ -147,7 +147,7 @@ long arch_ptrace(struct task_struct *child, long request,
/* The trampoline page is globally mapped, no page table to traverse.*/
tmp = *(unsigned long*)addr;
} else {
copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
copied = access_process_vm(child, addr, &tmp, sizeof(tmp), FOLL_FORCE);
if (copied != sizeof(tmp))
break;
@ -279,7 +279,7 @@ static int insn_size(struct task_struct *child, unsigned long pc)
int opsize = 0;
/* Read the opcode at pc (do what PTRACE_PEEKTEXT would do). */
copied = access_process_vm(child, pc, &opcode, sizeof(opcode), 0);
copied = access_process_vm(child, pc, &opcode, sizeof(opcode), FOLL_FORCE);
if (copied != sizeof(opcode))
return 0;

14
arch/ia64/kernel/ptrace.c
View File

@ -453,7 +453,7 @@ ia64_peek (struct task_struct *child, struct switch_stack *child_stack,
return 0;
}
}
copied = access_process_vm(child, addr, &ret, sizeof(ret), 0);
copied = access_process_vm(child, addr, &ret, sizeof(ret), FOLL_FORCE);
if (copied != sizeof(ret))
return -EIO;
*val = ret;
@ -489,7 +489,8 @@ ia64_poke (struct task_struct *child, struct switch_stack *child_stack,
*ia64_rse_skip_regs(krbs, regnum) = val;
}
}
} else if (access_process_vm(child, addr, &val, sizeof(val), 1)
} else if (access_process_vm(child, addr, &val, sizeof(val),
FOLL_FORCE | FOLL_WRITE)
!= sizeof(val))
return -EIO;
return 0;
@ -543,7 +544,8 @@ ia64_sync_user_rbs (struct task_struct *child, struct switch_stack *sw,
ret = ia64_peek(child, sw, user_rbs_end, addr, &val);
if (ret < 0)
return ret;
if (access_process_vm(child, addr, &val, sizeof(val), 1)
if (access_process_vm(child, addr, &val, sizeof(val),
FOLL_FORCE | FOLL_WRITE)
!= sizeof(val))
return -EIO;
}
@ -559,7 +561,8 @@ ia64_sync_kernel_rbs (struct task_struct *child, struct switch_stack *sw,
/* now copy word for word from user rbs to kernel rbs: */
for (addr = user_rbs_start; addr < user_rbs_end; addr += 8) {
if (access_process_vm(child, addr, &val, sizeof(val), 0)
if (access_process_vm(child, addr, &val, sizeof(val),
FOLL_FORCE)
!= sizeof(val))
return -EIO;
@ -1156,7 +1159,8 @@ arch_ptrace (struct task_struct *child, long request,
case PTRACE_PEEKTEXT:
case PTRACE_PEEKDATA:
/* read word at location addr */
if (access_process_vm(child, addr, &data, sizeof(data), 0)
if (access_process_vm(child, addr, &data, sizeof(data),
FOLL_FORCE)
!= sizeof(data))
return -EIO;
/* ensure return value is not mistaken for error code */

15
arch/m32r/kernel/ptrace.c
View File

@ -493,7 +493,8 @@ unregister_all_debug_traps(struct task_struct *child)
int i;
for (i = 0; i < p->nr_trap; i++)
access_process_vm(child, p->addr[i], &p->insn[i], sizeof(p->insn[i]), 1);
access_process_vm(child, p->addr[i], &p->insn[i], sizeof(p->insn[i]),
FOLL_FORCE | FOLL_WRITE);
p->nr_trap = 0;
}
@ -537,7 +538,8 @@ embed_debug_trap(struct task_struct *child, unsigned long next_pc)
unsigned long next_insn, code;
unsigned long addr = next_pc & ~3;
if (access_process_vm(child, addr, &next_insn, sizeof(next_insn), 0)
if (access_process_vm(child, addr, &next_insn, sizeof(next_insn),
FOLL_FORCE)
!= sizeof(next_insn)) {
return -1; /* error */
}
@ -546,7 +548,8 @@ embed_debug_trap(struct task_struct *child, unsigned long next_pc)
if (register_debug_trap(child, next_pc, next_insn, &code)) {
return -1; /* error */
}
if (access_process_vm(child, addr, &code, sizeof(code), 1)
if (access_process_vm(child, addr, &code, sizeof(code),
FOLL_FORCE | FOLL_WRITE)
!= sizeof(code)) {
return -1; /* error */
}
@ -562,7 +565,8 @@ withdraw_debug_trap(struct pt_regs *regs)
addr = (regs->bpc - 2) & ~3;
regs->bpc -= 2;
if (unregister_debug_trap(current, addr, &code)) {
access_process_vm(current, addr, &code, sizeof(code), 1);
access_process_vm(current, addr, &code, sizeof(code),
FOLL_FORCE | FOLL_WRITE);
invalidate_cache();
}
}
@ -589,7 +593,8 @@ void user_enable_single_step(struct task_struct *child)
/* Compute next pc. */
pc = get_stack_long(child, PT_BPC);
if (access_process_vm(child, pc&~3, &insn, sizeof(insn), 0)
if (access_process_vm(child, pc&~3, &insn, sizeof(insn),
FOLL_FORCE)
!= sizeof(insn))
return;

5
arch/mips/kernel/ptrace32.c
View File

@ -70,7 +70,7 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
break;
copied = access_process_vm(child, (u64)addrOthers, &tmp,
sizeof(tmp), 0);
sizeof(tmp), FOLL_FORCE);
if (copied != sizeof(tmp))
break;
ret = put_user(tmp, (u32 __user *) (unsigned long) data);
@ -179,7 +179,8 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
break;
ret = 0;
if (access_process_vm(child, (u64)addrOthers, &data,
sizeof(data), 1) == sizeof(data))
sizeof(data),
FOLL_FORCE | FOLL_WRITE) == sizeof(data))
break;
ret = -EIO;
break;

5
arch/powerpc/kernel/ptrace32.c
View File

@ -74,7 +74,7 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
break;
copied = access_process_vm(child, (u64)addrOthers, &tmp,
sizeof(tmp), 0);
sizeof(tmp), FOLL_FORCE);
if (copied != sizeof(tmp))
break;
ret = put_user(tmp, (u32 __user *)data);
@ -179,7 +179,8 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
break;
ret = 0;
if (access_process_vm(child, (u64)addrOthers, &tmp,
sizeof(tmp), 1) == sizeof(tmp))
sizeof(tmp),
FOLL_FORCE | FOLL_WRITE) == sizeof(tmp))
break;
ret = -EIO;
break;

10
arch/score/kernel/ptrace.c
View File

@ -131,7 +131,7 @@ read_tsk_long(struct task_struct *child,
{
int copied;
copied = access_process_vm(child, addr, res, sizeof(*res), 0);
copied = access_process_vm(child, addr, res, sizeof(*res), FOLL_FORCE);
return copied != sizeof(*res) ? -EIO : 0;
}
@ -142,7 +142,7 @@ read_tsk_short(struct task_struct *child,
{
int copied;
copied = access_process_vm(child, addr, res, sizeof(*res), 0);
copied = access_process_vm(child, addr, res, sizeof(*res), FOLL_FORCE);
return copied != sizeof(*res) ? -EIO : 0;
}
@ -153,7 +153,8 @@ write_tsk_short(struct task_struct *child,
{
int copied;
copied = access_process_vm(child, addr, &val, sizeof(val), 1);
copied = access_process_vm(child, addr, &val, sizeof(val),
FOLL_FORCE | FOLL_WRITE);
return copied != sizeof(val) ? -EIO : 0;
}
@ -164,7 +165,8 @@ write_tsk_long(struct task_struct *child,
{
int copied;
copied = access_process_vm(child, addr, &val, sizeof(val), 1);
copied = access_process_vm(child, addr, &val, sizeof(val),
FOLL_FORCE | FOLL_WRITE);
return copied != sizeof(val) ? -EIO : 0;
}

24
arch/sparc/kernel/ptrace_64.c
View File

@ -127,7 +127,8 @@ static int get_from_target(struct task_struct *target, unsigned long uaddr,
if (copy_from_user(kbuf, (void __user *) uaddr, len))
return -EFAULT;
} else {
int len2 = access_process_vm(target, uaddr, kbuf, len, 0);
int len2 = access_process_vm(target, uaddr, kbuf, len,
FOLL_FORCE);
if (len2 != len)
return -EFAULT;
}
@ -141,7 +142,8 @@ static int set_to_target(struct task_struct *target, unsigned long uaddr,
if (copy_to_user((void __user *) uaddr, kbuf, len))
return -EFAULT;
} else {
int len2 = access_process_vm(target, uaddr, kbuf, len, 1);
int len2 = access_process_vm(target, uaddr, kbuf, len,
FOLL_FORCE | FOLL_WRITE);
if (len2 != len)
return -EFAULT;
}
@ -505,7 +507,8 @@ static int genregs32_get(struct task_struct *target,
if (access_process_vm(target,
(unsigned long)
&reg_window[pos],
k, sizeof(*k), 0)
k, sizeof(*k),
FOLL_FORCE)
!= sizeof(*k))
return -EFAULT;
k++;
@ -531,12 +534,14 @@ static int genregs32_get(struct task_struct *target,
if (access_process_vm(target,
(unsigned long)
&reg_window[pos],
&reg, sizeof(reg), 0)
&reg, sizeof(reg),
FOLL_FORCE)
!= sizeof(reg))
return -EFAULT;
if (access_process_vm(target,
(unsigned long) u,
&reg, sizeof(reg), 1)
&reg, sizeof(reg),
FOLL_FORCE | FOLL_WRITE)
!= sizeof(reg))
return -EFAULT;
pos++;
@ -615,7 +620,8 @@ static int genregs32_set(struct task_struct *target,
(unsigned long)
&reg_window[pos],
(void *) k,
sizeof(*k), 1)
sizeof(*k),
FOLL_FORCE | FOLL_WRITE)
!= sizeof(*k))
return -EFAULT;
k++;
@ -642,13 +648,15 @@ static int genregs32_set(struct task_struct *target,
if (access_process_vm(target,
(unsigned long)
u,
&reg, sizeof(reg), 0)
&reg, sizeof(reg),
FOLL_FORCE)
!= sizeof(reg))
return -EFAULT;
if (access_process_vm(target,
(unsigned long)
&reg_window[pos],
&reg, sizeof(reg), 1)
&reg, sizeof(reg),
FOLL_FORCE | FOLL_WRITE)
!= sizeof(reg))
return -EFAULT;
pos++;

3
arch/x86/kernel/step.c
View File

@ -57,7 +57,8 @@ static int is_setting_trap_flag(struct task_struct *child, struct pt_regs *regs)
unsigned char opcode[15];
unsigned long addr = convert_ip_to_linear(child, regs);
copied = access_process_vm(child, addr, opcode, sizeof(opcode), 0);
copied = access_process_vm(child, addr, opcode, sizeof(opcode),
FOLL_FORCE);
for (i = 0; i < copied; i++) {
switch (opcode[i]) {
/* popf and iret */

3
arch/x86/um/ptrace_32.c
View File

@ -36,7 +36,8 @@ int is_syscall(unsigned long addr)
* slow, but that doesn't matter, since it will be called only
* in case of singlestepping, if copy_from_user failed.
*/
n = access_process_vm(current, addr, &instr, sizeof(instr), 0);
n = access_process_vm(current, addr, &instr, sizeof(instr),
FOLL_FORCE);
if (n != sizeof(instr)) {
printk(KERN_ERR "is_syscall : failed to read "
"instruction from 0x%lx\n", addr);

3
arch/x86/um/ptrace_64.c
View File

@ -212,7 +212,8 @@ int is_syscall(unsigned long addr)
* slow, but that doesn't matter, since it will be called only
* in case of singlestepping, if copy_from_user failed.
*/
n = access_process_vm(current, addr, &instr, sizeof(instr), 0);
n = access_process_vm(current, addr, &instr, sizeof(instr),
FOLL_FORCE);
if (n != sizeof(instr)) {
printk("is_syscall : failed to read instruction from "
"0x%lx\n", addr);

3
include/linux/mm.h
View File

@ -1266,7 +1266,8 @@ static inline int fixup_user_fault(struct task_struct *tsk,
}
#endif
extern int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write);
extern int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len,
unsigned int gup_flags);
extern int access_remote_vm(struct mm_struct *mm, unsigned long addr,
void *buf, int len, unsigned int gup_flags);

16
kernel/ptrace.c
View File

@ -537,7 +537,7 @@ int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst
int this_len, retval;
this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
retval = access_process_vm(tsk, src, buf, this_len, 0);
retval = access_process_vm(tsk, src, buf, this_len, FOLL_FORCE);
if (!retval) {
if (copied)
break;
@ -564,7 +564,8 @@ int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long ds
this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
if (copy_from_user(buf, src, this_len))
return -EFAULT;
retval = access_process_vm(tsk, dst, buf, this_len, 1);
retval = access_process_vm(tsk, dst, buf, this_len,
FOLL_FORCE | FOLL_WRITE);
if (!retval) {
if (copied)
break;
@ -1127,7 +1128,7 @@ int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
unsigned long tmp;
int copied;
copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0);
copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), FOLL_FORCE);
if (copied != sizeof(tmp))
return -EIO;
return put_user(tmp, (unsigned long __user *)data);
@ -1138,7 +1139,8 @@ int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
{
int copied;
copied = access_process_vm(tsk, addr, &data, sizeof(data), 1);
copied = access_process_vm(tsk, addr, &data, sizeof(data),
FOLL_FORCE | FOLL_WRITE);
return (copied == sizeof(data)) ? 0 : -EIO;
}
@ -1155,7 +1157,8 @@ int compat_ptrace_request(struct task_struct *child, compat_long_t request,
switch (request) {
case PTRACE_PEEKTEXT:
case PTRACE_PEEKDATA:
ret = access_process_vm(child, addr, &word, sizeof(word), 0);
ret = access_process_vm(child, addr, &word, sizeof(word),
FOLL_FORCE);
if (ret != sizeof(word))
ret = -EIO;
else
@ -1164,7 +1167,8 @@ int compat_ptrace_request(struct task_struct *child, compat_long_t request,
case PTRACE_POKETEXT:
case PTRACE_POKEDATA:
ret = access_process_vm(child, addr, &data, sizeof(data), 1);
ret = access_process_vm(child, addr, &data, sizeof(data),
FOLL_FORCE | FOLL_WRITE);
ret = (ret != sizeof(data) ? -EIO : 0);
break;

8
mm/memory.c
View File

@ -3951,20 +3951,16 @@ int access_remote_vm(struct mm_struct *mm, unsigned long addr,
* Do not walk the page table directly, use get_user_pages
*/
int access_process_vm(struct task_struct *tsk, unsigned long addr,
void *buf, int len, int write)
void *buf, int len, unsigned int gup_flags)
{
struct mm_struct *mm;
int ret;
unsigned int flags = FOLL_FORCE;
mm = get_task_mm(tsk);
if (!mm)
return 0;
if (write)
flags |= FOLL_WRITE;
ret = __access_remote_vm(tsk, mm, addr, buf, len, flags);
ret = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags);
mmput(mm);

6
mm/nommu.c
View File

@ -1861,7 +1861,8 @@ int access_remote_vm(struct mm_struct *mm, unsigned long addr,
* Access another process' address space.
* - source/target buffer must be kernel space
*/
int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len,
unsigned int gup_flags)
{
struct mm_struct *mm;
@ -1872,8 +1873,7 @@ int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, in
if (!mm)
return 0;
len = __access_remote_vm(tsk, mm, addr, buf, len,
write ? FOLL_WRITE : 0);
len = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags);
mmput(mm);
return len;

5
mm/util.c
View File

@ -624,7 +624,7 @@ int get_cmdline(struct task_struct *task, char *buffer, int buflen)
if (len > buflen)
len = buflen;
res = access_process_vm(task, arg_start, buffer, len, 0);
res = access_process_vm(task, arg_start, buffer, len, FOLL_FORCE);
/*
* If the nul at the end of args has been overwritten, then
@ -639,7 +639,8 @@ int get_cmdline(struct task_struct *task, char *buffer, int buflen)
if (len > buflen - res)
len = buflen - res;
res += access_process_vm(task, env_start,
buffer+res, len, 0);
buffer+res, len,
FOLL_FORCE);
res = strnlen(buffer, res);
}
}