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Howlett" Subject: [PATCH v2 6.1] mm/mempolicy: fix migrate_to_node() assuming there is at least one VMA in a MM Date: Fri, 7 Mar 2025 15:28:04 +0300 Message-Id: <20250307122804.10548-1-apanov@astralinux.ru> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 X-KSMG-AntiPhishing: NotDetected, bases: 2025/03/07 11:11:00 X-KSMG-AntiSpam-Auth: dkim=none X-KSMG-AntiSpam-Envelope-From: apanov@astralinux.ru X-KSMG-AntiSpam-Info: LuaCore: 51 0.3.51 68896fb0083a027476849bf400a331a2d5d94398, {Tracking_uf_ne_domains}, {Tracking_internal2}, {Tracking_from_domain_doesnt_match_to}, astralinux.ru:7.1.1;lore.kernel.org:7.1.1;d41d8cd98f00b204e9800998ecf8427e.com:7.1.1;127.0.0.199:7.1.2;new-mail.astralinux.ru:7.1.1;lkml.kernel.org:7.1.1, FromAlignment: s X-KSMG-AntiSpam-Interceptor-Info: scan successful X-KSMG-AntiSpam-Lua-Profiles: 191572 [Mar 07 2025] X-KSMG-AntiSpam-Method: none X-KSMG-AntiSpam-Rate: 0 X-KSMG-AntiSpam-Status: not_detected X-KSMG-AntiSpam-Version: 6.1.1.11 X-KSMG-AntiVirus: Kaspersky Secure Mail Gateway, version 2.1.0.7854, bases: 2025/03/07 09:54:00 #27658601 X-KSMG-AntiVirus-Status: NotDetected, skipped X-KSMG-LinksScanning: NotDetected, bases: 2025/03/07 11:11:00 X-KSMG-Message-Action: skipped X-KSMG-Rule-ID: 1 X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 5D96B20008 X-Rspam-User: X-Stat-Signature: omio3iir3xctk483gwa3towfu5t5crji X-HE-Tag: 1741350503-764765 X-HE-Meta: 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 t4VOeBWr 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: David Hildenbrand 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: 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@linux-foundation.org: add unlikely()] Link: https://lkml.kernel.org/r/20241120201151.9518-1-david@redhat.com Fixes: 39743889aaf7 ("[PATCH] Swap Migration V5: sys_migrate_pages interface") Signed-off-by: David Hildenbrand Reported-by: syzbot+3511625422f7aa637f0d@syzkaller.appspotmail.com Closes: https://lore.kernel.org/lkml/673d2696.050a0220.3c9d61.012f.GAE@google.com/T/ Reviewed-by: Liam R. Howlett Reviewed-by: Christoph Lameter Cc: Liam R. Howlett Cc: Signed-off-by: Andrew Morton [ Alexey: mmap_read_lock is not used in this context, so mmap_read_unlock is removed. Synchronization is provided by an external context in do_migrate_pages(). ] Signed-off-by: Alexey Panov --- v2: Clarify mmap_lock context in changes summary. Fix braces for a single statement block. Rearrange the changes with a comment and VM_BUG_ON to look more consistent with upstream. mm/mempolicy.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 399d8cb48813..f60ff4727f46 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -1062,13 +1062,17 @@ static int migrate_to_node(struct mm_struct *mm, int source, int dest, nodes_clear(nmask); node_set(source, nmask); + VM_BUG_ON(!(flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL))); + + vma = find_vma(mm, 0); + if (unlikely(!vma)) + return 0; + /* * This does not "check" the range but isolates all pages that * need migration. Between passing in the full user address * space range and MPOL_MF_DISCONTIG_OK, this call can not fail. */ - vma = find_vma(mm, 0); - VM_BUG_ON(!(flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL))); queue_pages_range(mm, vma->vm_start, mm->task_size, &nmask, flags | MPOL_MF_DISCONTIG_OK, &pagelist);