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| author | David Gibson <david@gibson.dropbear.id.au> | 2005-11-29 19:34:32 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-11-29 19:47:03 -0800 |
| commit | 5bd0190bf3d7e53043a048e809ffa29d41b9d6ac (patch) | |
| tree | c6fba8d5a532ecfa53dc97a3841d13d972964854 /kernel | |
| parent | df69a60dc6afc2936d79054d30b481c1fd9720e5 (diff) | |
| download | lwn-5bd0190bf3d7e53043a048e809ffa29d41b9d6ac.tar.gz lwn-5bd0190bf3d7e53043a048e809ffa29d41b9d6ac.zip | |
[PATCH] Fix crash when ptrace poking hugepage areas
set_page_dirty() will not cope with being handed a page * which is part of
a compound page, but not the master page in that compound page. This case
can occur via access_process_vm() if you attemp to write to another
process's hugepage memory area using ptrace() (causing an oops or hang).
This patch fixes the bug by only calling set_page_dirty() from
access_process_vm() if the page is not a compound page. We already use a
similar fix in bio_set_pages_dirty() for the case of direct io to
hugepages.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Acked-by: William Irwin <wli@holomorphy.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/ptrace.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 17ee7e5a3451..656476eedb1b 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -241,7 +241,8 @@ int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, in if (write) { copy_to_user_page(vma, page, addr, maddr + offset, buf, bytes); - set_page_dirty_lock(page); + if (!PageCompound(page)) + set_page_dirty_lock(page); } else { copy_from_user_page(vma, page, addr, buf, maddr + offset, bytes); |