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 <[email protected]>
Acked-by: Jesper Nilsson <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Acked-by: Michael Ellerman <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Lorenzo Stoakes 2016-10-13 01:20:20 +01:00 • committed by Linus Torvalds
commit f307ab6dce
17 changed files with 84 additions and 54 deletions

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 */

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);

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);