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authorHugh Dickins <hugh@veritas.com>2005-08-02 00:11:42 -0400
committerLinus Torvalds <torvalds@g5.osdl.org>2005-08-02 00:38:00 -0400
commit690dbe1ced143876d8fa56b72310738dbe079d0a (patch)
tree4297d5647ce5e6cbe429dc506007579952c31015 /mm/memory.c
parent74f9c9c258249fba3e2e78f70691528426a6c010 (diff)
[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>
Diffstat (limited to 'mm/memory.c')
-rw-r--r--mm/memory.c8
1 files changed, 6 insertions, 2 deletions
diff --git a/mm/memory.c b/mm/memory.c
index 4e1c673784db..2405289dfdf8 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,
910 pud = pud_offset(pgd, pg); 910 pud = pud_offset(pgd, pg);
911 BUG_ON(pud_none(*pud)); 911 BUG_ON(pud_none(*pud));
912 pmd = pmd_offset(pud, pg); 912 pmd = pmd_offset(pud, pg);
913 BUG_ON(pmd_none(*pmd)); 913 if (pmd_none(*pmd))
914 return i ? : -EFAULT;
914 pte = pte_offset_map(pmd, pg); 915 pte = pte_offset_map(pmd, pg);
915 BUG_ON(pte_none(*pte)); 916 if (pte_none(*pte)) {
917 pte_unmap(pte);
918 return i ? : -EFAULT;
919 }
916 if (pages) { 920 if (pages) {
917 pages[i] = pte_page(*pte); 921 pages[i] = pte_page(*pte);
918 get_page(pages[i]); 922 get_page(pages[i]);