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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>
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parent
07d9a38068
commit
272ddc8b37
1 changed files with 8 additions and 10 deletions
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@ -252,7 +252,7 @@ static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf,
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* Inherently racy -- command line shares address space
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* Inherently racy -- command line shares address space
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* with code and data.
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* with code and data.
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*/
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*/
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rv = access_remote_vm(mm, arg_end - 1, &c, 1, FOLL_FORCE);
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rv = access_remote_vm(mm, arg_end - 1, &c, 1, 0);
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if (rv <= 0)
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if (rv <= 0)
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goto out_free_page;
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goto out_free_page;
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@ -270,8 +270,7 @@ static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf,
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int nr_read;
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int nr_read;
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_count = min3(count, len, PAGE_SIZE);
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_count = min3(count, len, PAGE_SIZE);
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nr_read = access_remote_vm(mm, p, page, _count,
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nr_read = access_remote_vm(mm, p, page, _count, 0);
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FOLL_FORCE);
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if (nr_read < 0)
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if (nr_read < 0)
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rv = nr_read;
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rv = nr_read;
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if (nr_read <= 0)
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if (nr_read <= 0)
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@ -306,8 +305,7 @@ static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf,
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bool final;
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bool final;
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_count = min3(count, len, PAGE_SIZE);
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_count = min3(count, len, PAGE_SIZE);
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nr_read = access_remote_vm(mm, p, page, _count,
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nr_read = access_remote_vm(mm, p, page, _count, 0);
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FOLL_FORCE);
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if (nr_read < 0)
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if (nr_read < 0)
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rv = nr_read;
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rv = nr_read;
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if (nr_read <= 0)
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if (nr_read <= 0)
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@ -356,8 +354,7 @@ static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf,
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bool final;
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bool final;
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_count = min3(count, len, PAGE_SIZE);
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_count = min3(count, len, PAGE_SIZE);
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nr_read = access_remote_vm(mm, p, page, _count,
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nr_read = access_remote_vm(mm, p, page, _count, 0);
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FOLL_FORCE);
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if (nr_read < 0)
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if (nr_read < 0)
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rv = nr_read;
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rv = nr_read;
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if (nr_read <= 0)
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if (nr_read <= 0)
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@ -835,7 +832,7 @@ static ssize_t mem_rw(struct file *file, char __user *buf,
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unsigned long addr = *ppos;
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unsigned long addr = *ppos;
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ssize_t copied;
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ssize_t copied;
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char *page;
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char *page;
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unsigned int flags = FOLL_FORCE;
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unsigned int flags;
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if (!mm)
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if (!mm)
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return 0;
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return 0;
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@ -848,6 +845,8 @@ static ssize_t mem_rw(struct file *file, char __user *buf,
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if (!atomic_inc_not_zero(&mm->mm_users))
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if (!atomic_inc_not_zero(&mm->mm_users))
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goto free;
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goto free;
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/* Maybe we should limit FOLL_FORCE to actual ptrace users? */
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flags = FOLL_FORCE;
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if (write)
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if (write)
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flags |= FOLL_WRITE;
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flags |= FOLL_WRITE;
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@ -971,8 +970,7 @@ static ssize_t environ_read(struct file *file, char __user *buf,
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max_len = min_t(size_t, PAGE_SIZE, count);
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max_len = min_t(size_t, PAGE_SIZE, count);
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this_len = min(max_len, this_len);
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this_len = min(max_len, this_len);
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retval = access_remote_vm(mm, (env_start + src),
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retval = access_remote_vm(mm, (env_start + src), page, this_len, 0);
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page, this_len, FOLL_FORCE);
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if (retval <= 0) {
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if (retval <= 0) {
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ret = retval;
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ret = retval;
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