6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Hildenbrand <david@xxxxxxxxxx> commit 091c1dd2d4df6edd1beebe0e5863d4034ade9572 upstream. We currently assume that there is at least one VMA in a MM, which isn't true. So we might end up having find_vma() return NULL, to then de-reference NULL. So properly handle find_vma() returning NULL. This fixes the report: Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] CPU: 1 UID: 0 PID: 6021 Comm: syz-executor284 Not tainted 6.12.0-rc7-syzkaller-00187-gf868cd251776 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024 RIP: 0010:migrate_to_node mm/mempolicy.c:1090 [inline] RIP: 0010:do_migrate_pages+0x403/0x6f0 mm/mempolicy.c:1194 Code: ... RSP: 0018:ffffc9000375fd08 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffffc9000375fd78 RCX: 0000000000000000 RDX: ffff88807e171300 RSI: dffffc0000000000 RDI: ffff88803390c044 RBP: ffff88807e171428 R08: 0000000000000014 R09: fffffbfff2039ef1 R10: ffffffff901cf78f R11: 0000000000000000 R12: 0000000000000003 R13: ffffc9000375fe90 R14: ffffc9000375fe98 R15: ffffc9000375fdf8 FS: 00005555919e1380(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00005555919e1ca8 CR3: 000000007f12a000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> kernel_migrate_pages+0x5b2/0x750 mm/mempolicy.c:1709 __do_sys_migrate_pages mm/mempolicy.c:1727 [inline] __se_sys_migrate_pages mm/mempolicy.c:1723 [inline] __x64_sys_migrate_pages+0x96/0x100 mm/mempolicy.c:1723 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f [akpm@xxxxxxxxxxxxxxxxxxxx: add unlikely()] Link: https://lkml.kernel.org/r/20241120201151.9518-1-david@xxxxxxxxxx Fixes: 39743889aaf7 ("[PATCH] Swap Migration V5: sys_migrate_pages interface") Signed-off-by: David Hildenbrand <david@xxxxxxxxxx> Reported-by: syzbot+3511625422f7aa637f0d@xxxxxxxxxxxxxxxxxxxxxxxxx Closes: https://lore.kernel.org/lkml/673d2696.050a0220.3c9d61.012f.GAE@xxxxxxxxxx/T/ Reviewed-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx> Reviewed-by: Christoph Lameter <cl@xxxxxxxxx> Cc: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- mm/mempolicy.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -1080,6 +1080,10 @@ static long migrate_to_node(struct mm_st mmap_read_lock(mm); vma = find_vma(mm, 0); + if (unlikely(!vma)) { + mmap_read_unlock(mm); + return 0; + } /* * This does not migrate the range, but isolates all pages that
