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authorLinus Torvalds <torvalds@linux-foundation.org>2016-10-24 19:00:44 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-10-24 19:00:44 -0700
commit272ddc8b37354c3fe111ab26d25e792629148eee (patch)
tree78d4280320fbee5b4b37a839023b6a9ba34865ef /fs
parent07d9a380680d1c0eb51ef87ff2eab5c994949e69 (diff)
proc: don't use FOLL_FORCE for reading cmdline and environment
Now that Lorenzo cleaned things up and made the FOLL_FORCE users explicit, it becomes obvious how some of them don't really need FOLL_FORCE at all. So remove FOLL_FORCE from the proc code that reads the command line and arguments from user space. The mem_rw() function actually does want FOLL_FORCE, because gdd (and possibly many other debuggers) use it as a much more convenient version of PTRACE_PEEKDATA, but we should consider making the FOLL_FORCE part conditional on actually being a ptracer. This does not actually do that, just moves adds a comment to that effect and moves the gup_flags settings next to each other. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/proc/base.c18
1 files changed, 8 insertions, 10 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 8e654468ab67..adfc5b4986f5 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -252,7 +252,7 @@ static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf,
* Inherently racy -- command line shares address space
* with code and data.
*/
- rv = access_remote_vm(mm, arg_end - 1, &c, 1, FOLL_FORCE);
+ rv = access_remote_vm(mm, arg_end - 1, &c, 1, 0);
if (rv <= 0)
goto out_free_page;
@@ -270,8 +270,7 @@ static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf,
int nr_read;
_count = min3(count, len, PAGE_SIZE);
- nr_read = access_remote_vm(mm, p, page, _count,
- FOLL_FORCE);
+ nr_read = access_remote_vm(mm, p, page, _count, 0);
if (nr_read < 0)
rv = nr_read;
if (nr_read <= 0)
@@ -306,8 +305,7 @@ static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf,
bool final;
_count = min3(count, len, PAGE_SIZE);
- nr_read = access_remote_vm(mm, p, page, _count,
- FOLL_FORCE);
+ nr_read = access_remote_vm(mm, p, page, _count, 0);
if (nr_read < 0)
rv = nr_read;
if (nr_read <= 0)
@@ -356,8 +354,7 @@ skip_argv:
bool final;
_count = min3(count, len, PAGE_SIZE);
- nr_read = access_remote_vm(mm, p, page, _count,
- FOLL_FORCE);
+ nr_read = access_remote_vm(mm, p, page, _count, 0);
if (nr_read < 0)
rv = nr_read;
if (nr_read <= 0)
@@ -835,7 +832,7 @@ static ssize_t mem_rw(struct file *file, char __user *buf,
unsigned long addr = *ppos;
ssize_t copied;
char *page;
- unsigned int flags = FOLL_FORCE;
+ unsigned int flags;
if (!mm)
return 0;
@@ -848,6 +845,8 @@ static ssize_t mem_rw(struct file *file, char __user *buf,
if (!atomic_inc_not_zero(&mm->mm_users))
goto free;
+ /* Maybe we should limit FOLL_FORCE to actual ptrace users? */
+ flags = FOLL_FORCE;
if (write)
flags |= FOLL_WRITE;
@@ -971,8 +970,7 @@ static ssize_t environ_read(struct file *file, char __user *buf,
max_len = min_t(size_t, PAGE_SIZE, count);
this_len = min(max_len, this_len);
- retval = access_remote_vm(mm, (env_start + src),
- page, this_len, FOLL_FORCE);
+ retval = access_remote_vm(mm, (env_start + src), page, this_len, 0);
if (retval <= 0) {
ret = retval;