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authorDavid Gibson <david@gibson.dropbear.id.au>2005-11-29 19:34:32 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2005-11-29 19:47:03 -0800
commit5bd0190bf3d7e53043a048e809ffa29d41b9d6ac (patch)
treec6fba8d5a532ecfa53dc97a3841d13d972964854 /kernel/ptrace.c
parentdf69a60dc6afc2936d79054d30b481c1fd9720e5 (diff)
[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/ptrace.c')
-rw-r--r--kernel/ptrace.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 17ee7e5a345..656476eedb1 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);