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authorLorenzo Stoakes <lstoakes@gmail.com>2016-10-13 01:20:20 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2016-10-19 08:31:25 -0700
commitf307ab6dcea03f9d8e4d70508fd7d1ca57cfa7f9 (patch)
tree94a96ebae9957cf1252231a69f8904796aa2563e /mm
parent6347e8d5bcce33fc36e651901efefbe2c93a43ef (diff)
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>
Diffstat (limited to 'mm')
-rw-r--r--mm/memory.c8
-rw-r--r--mm/nommu.c6
-rw-r--r--mm/util.c5
3 files changed, 8 insertions, 11 deletions
diff --git a/mm/memory.c b/mm/memory.c
index bac2d994850e..e18c57bdc75c 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -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);
diff --git a/mm/nommu.c b/mm/nommu.c
index 93d5bb53fc63..db5fd1795298 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -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;
diff --git a/mm/util.c b/mm/util.c
index 4c685bde5ebc..952cbe7ad7b7 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -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);
}
}