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pagemap: proper read error handling 

Fix pagemap_read() error handling by releasing acquired resources and checking
for get_user_pages() partial failure.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Acked-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Marcelo Tosatti 2008-03-13 12:32:35 -07:00 committed by Linus Torvalds
parent b500ce8d24
commit fb39380b8d
1 changed files with 13 additions and 5 deletions
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18
fs/proc/task_mmu.c
View File

@ -640,17 +640,17 @@ static ssize_t pagemap_read(struct file *file, char __user *buf,
ret = -EACCES; ret = -EACCES;
if (!ptrace_may_attach(task)) if (!ptrace_may_attach(task))
goto out; goto out_task;
ret = -EINVAL; ret = -EINVAL;
/* file position must be aligned */ /* file position must be aligned */
if (*ppos % PM_ENTRY_BYTES) if (*ppos % PM_ENTRY_BYTES)
goto out; goto out_task;
ret = 0; ret = 0;
mm = get_task_mm(task); mm = get_task_mm(task);
if (!mm) if (!mm)
goto out; goto out_task;
ret = -ENOMEM; ret = -ENOMEM;
uaddr = (unsigned long)buf & PAGE_MASK; uaddr = (unsigned long)buf & PAGE_MASK;
@ -658,7 +658,7 @@ static ssize_t pagemap_read(struct file *file, char __user *buf,
pagecount = (PAGE_ALIGN(uend) - uaddr) / PAGE_SIZE; pagecount = (PAGE_ALIGN(uend) - uaddr) / PAGE_SIZE;
pages = kmalloc(pagecount * sizeof(struct page *), GFP_KERNEL); pages = kmalloc(pagecount * sizeof(struct page *), GFP_KERNEL);
if (!pages) if (!pages)
goto out_task; goto out_mm;
down_read(&current->mm->mmap_sem); down_read(&current->mm->mmap_sem);
ret = get_user_pages(current, current->mm, uaddr, pagecount, ret = get_user_pages(current, current->mm, uaddr, pagecount,
@ -668,6 +668,12 @@ static ssize_t pagemap_read(struct file *file, char __user *buf,
if (ret < 0) if (ret < 0)
goto out_free; goto out_free;
if (ret != pagecount) {
pagecount = ret;
ret = -EFAULT;
goto out_pages;
}
pm.out = buf; pm.out = buf;
pm.end = buf + count; pm.end = buf + count;
@ -699,15 +705,17 @@ static ssize_t pagemap_read(struct file *file, char __user *buf,
ret = pm.out - buf; ret = pm.out - buf;
} }
out_pages:
for (; pagecount; pagecount--) { for (; pagecount; pagecount--) {
page = pages[pagecount-1]; page = pages[pagecount-1];
if (!PageReserved(page)) if (!PageReserved(page))
SetPageDirty(page); SetPageDirty(page);
page_cache_release(page); page_cache_release(page);
} }
mmput(mm);
out_free: out_free:
kfree(pages); kfree(pages);
out_mm:
mmput(mm);
out_task: out_task:
put_task_struct(task); put_task_struct(task);
out: out: