[syzbot] [raid?] WARNING in r1buf_pool_alloc

[syzbot] [raid?] WARNING in r1buf_pool_alloc

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    23c62304dde2 Merge tag 'for-linus-7.4a-rc3-tag' of git://g..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=142ac5be580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=1cf189394a856f11
dashboard link: https://syzkaller.appspot.com/bug?extid=c0e700c08ee88f60e54d
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=178e7da1580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=162f644d580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-23c62304.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0f7bce229a50/vmlinux-23c62304.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7a152fd539c6/bzImage-23c62304.xz

AI-generated root cause summary:
When configuring a software RAID1 array via the SET_ARRAY_INFO ioctl,
md_set_array_info() in drivers/md/md.c does not validate the user-supplied
info->raid_disks value. When an array is initialized with an excessively large
raid_disks count (e.g. 0x8002 / 32,770), the resync initialization in
raid1_sync_request() invokes r1buf_pool_alloc() in drivers/md/raid1.c to
preallocate mempool buffers. r1buf_pool_alloc() attempts to allocate an array of
struct resync_pages via kmalloc_objs(..., conf->raid_disks * 2, ...) exceeding
KMALLOC_MAX_SIZE (4 MiB), which triggers the WARN_ON_ONCE_GFP check in
___kmalloc_large_node() in mm/slub.c.

full analysis:  https://syzkaller.appspot.com/x/ai_root_cause?x=c0e700c08ee88f60e54d

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c0e700c08ee88f60e54d@syzkaller.appspotmail.com

md: resync of RAID array md0
------------[ cut here ]------------
1
WARNING: mm/slub.c:5459 at ___kmalloc_large_node+0x132/0x170 mm/slub.c:5459, CPU#2: md0_resync/6011
Modules linked in:
CPU: 2 UID: 0 PID: 6011 Comm: md0_resync Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:___kmalloc_large_node+0x132/0x170 mm/slub.c:5459
Code: db 0f 85 66 ff ff ff 45 31 e4 eb cb 48 81 ff 00 00 40 00 0f 86 07 ff ff ff 80 3d 51 7d d6 0f 00 75 0b c6 05 48 7d d6 0f 01 90 <0f> 0b 90 48 83 c4 08 31 c0 5b 5d 41 5c 41 5d 41 5e c3 cc cc cc cc
RSP: 0018:ffffc90003cf7608 EFLAGS: 00010246
RAX: ffffffff88996c0e RBX: 0000000000880220 RCX: 0000000000000000
RDX: 00000000ffffffff RSI: 0000000000000cc0 RDI: 0000000000880220
RBP: 0000000000000cc0 R08: 0000000000000000 R09: 0000000000000000
R10: ffffed100c6b000e R11: 0000000000000000 R12: 0000000000000cc0
R13: 00000000ffffffff R14: 0000000000880220 R15: ffffed10048c1435
FS:  0000000000000000(0000) GS:ffff8880d466c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055559223fa28 CR3: 000000000fd98000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 __kmalloc_large_node_noprof+0x1c/0x70 mm/slub.c:5502
 __do_kmalloc_node mm/slub.c:5519 [inline]
 __kmalloc_noprof+0x5a3/0x840 mm/slub.c:5556
 _kmalloc_noprof include/linux/slab.h:995 [inline]
 r1buf_pool_alloc+0xfe/0xd90 drivers/md/raid1.c:181
 mempool_init_node+0x2f7/0x6f0 mm/mempool.c:272
 mempool_init_noprof+0x3a/0x50 mm/mempool.c:302
 init_resync drivers/md/raid1.c:2684 [inline]
 raid1_sync_request+0x1f5e/0x2ff0 drivers/md/raid1.c:2734
 md_do_sync.cold+0xf79/0x2946 drivers/md/md.c:9962
 md_thread+0x550/0x5d0 drivers/md/md.c:8732
 kthread+0x373/0x450 kernel/kthread.c:436
 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>


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