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Howlett" Subject: [PATCH v2 5.10/5.15] mm/mempolicy: fix migrate_to_node() assuming there is at least one VMA in a MM Date: Fri, 7 Mar 2025 15:28:30 +0300 Message-Id: <20250307122830.10655-1-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}, new-mail.astralinux.ru:7.1.1;d41d8cd98f00b204e9800998ecf8427e.com:7.1.1;127.0.0.199:7.1.2;astralinux.ru:7.1.1;lkml.kernel.org:7.1.1;lore.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-Stat-Signature: q31notue5csregnn9p6sxjdjtxo3mcoq X-Rspamd-Queue-Id: DD0C6C0004 X-Rspamd-Server: rspam06 X-Rspam-User: X-HE-Tag: 1741350515-234539 X-HE-Meta: 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 ZPKEjUOf 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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(). find_vma(mm, 0) is the same as mm->mmap. ] 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 | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 6c98585f20df..db94aec0ea17 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -1067,6 +1067,7 @@ static int migrate_to_node(struct mm_struct *mm, int source, int dest, int flags) { nodemask_t nmask; + struct vm_area_struct *vma; LIST_HEAD(pagelist); int err = 0; struct migration_target_control mtc = { @@ -1077,13 +1078,18 @@ 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. */ - VM_BUG_ON(!(flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL))); - queue_pages_range(mm, mm->mmap->vm_start, mm->task_size, &nmask, + queue_pages_range(mm, vma->vm_start, mm->task_size, &nmask, flags | MPOL_MF_DISCONTIG_OK, &pagelist); if (!list_empty(&pagelist)) {