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authorHugh Dickins <hugh@veritas.com>2005-08-01 21:11:42 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2005-08-01 21:38:00 -0700
commit690dbe1ced143876d8fa56b72310738dbe079d0a (patch)
tree4297d5647ce5e6cbe429dc506007579952c31015
parent74f9c9c258249fba3e2e78f70691528426a6c010 (diff)
downloadconfigs-690dbe1ced143876d8fa56b72310738dbe079d0a.tar.gz
[PATCH] x86_64: access of some bad address
x86_64 has a large sparse gate area between VSYSCALL_START and VSYSCALL_END, not all of it presently backed by pmds. Alexander Nyberg has found that in some circumstances gdb may try to ptrace here, and hit get_user_pages BUG_ON. It seems odd that gdb should be accessing here, but it certainly shouldn't crash in this way: relax BUG_ON to -EFAULT. Fixes kernel bugzilla #4801. Signed-off-by: Hugh Dickins <hugh@veritas.com> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--mm/memory.c8
1 files changed, 6 insertions, 2 deletions
diff --git a/mm/memory.c b/mm/memory.c
index 4e1c673784d..2405289dfdf 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -910,9 +910,13 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
pud = pud_offset(pgd, pg);
BUG_ON(pud_none(*pud));
pmd = pmd_offset(pud, pg);
- BUG_ON(pmd_none(*pmd));
+ if (pmd_none(*pmd))
+ return i ? : -EFAULT;
pte = pte_offset_map(pmd, pg);
- BUG_ON(pte_none(*pte));
+ if (pte_none(*pte)) {
+ pte_unmap(pte);
+ return i ? : -EFAULT;
+ }
if (pages) {
pages[i] = pte_page(*pte);
get_page(pages[i]);