AcoSail/kernel_optimize_test
8
0
Fork 0
forked from luck/tmp_suning_uos_patched
Code Pull Requests Activity

uprobes: __replace_page() avoid BUG in munlock_vma_page()

Browse Source 
syzbot crashed on the VM_BUG_ON_PAGE(PageTail) in munlock_vma_page(), when
called from uprobes __replace_page().  Which of many ways to fix it?
Settled on not calling when PageCompound (since Head and Tail are equals
in this context, PageCompound the usual check in uprobes.c, and the prior
use of FOLL_SPLIT_PMD will have cleared PageMlocked already).

Fixes: 5a52c9df62 ("uprobe: use FOLL_SPLIT_PMD instead of FOLL_SPLIT")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: <stable@vger.kernel.org>	[5.4+]
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2008161338360.20413@eggly.anvils
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Hugh Dickins 2020-08-20 17:42:17 -07:00 committed by Linus Torvalds
parent 71e843295c
commit c17c3dc9d0
1 changed files with 1 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
kernel/events/uprobes.c
View File

@ -205,7 +205,7 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
try_to_free_swap(old_page);
page_vma_mapped_walk_done(&pvmw);
if (vma->vm_flags & VM_LOCKED)
if ((vma->vm_flags & VM_LOCKED) && !PageCompound(old_page))
munlock_vma_page(old_page);
put_page(old_page);