From: Xiongwei Song <sxwjean@xxxxxxxxx> [ Upstream commit 545a32498c536ee152331cd2e7d2416aa0f20e01 ] We need to check the max request size that is from user space before allocating pages. If the request size exceeds the limit, return -EINVAL. This check can avoid the warning below from page allocator. WARNING: CPU: 3 PID: 16525 at mm/page_alloc.c:5344 current_gfp_context include/linux/sched/mm.h:195 [inline] WARNING: CPU: 3 PID: 16525 at mm/page_alloc.c:5344 __alloc_pages+0x45d/0x500 mm/page_alloc.c:5356 Modules linked in: CPU: 3 PID: 16525 Comm: syz-executor.3 Not tainted 5.15.0-syzkaller #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014 RIP: 0010:__alloc_pages+0x45d/0x500 mm/page_alloc.c:5344 Code: be c9 00 00 00 48 c7 c7 20 4a 97 89 c6 05 62 32 a7 0b 01 e8 74 9a 42 07 e9 6a ff ff ff 0f 0b e9 a0 fd ff ff 40 80 e5 3f eb 88 <0f> 0b e9 18 ff ff ff 4c 89 ef 44 89 e6 45 31 ed e8 1e 76 ff ff e9 RSP: 0018:ffffc90023b87850 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 1ffff92004770f0b RCX: dffffc0000000000 RDX: 0000000000000000 RSI: 0000000000000033 RDI: 0000000000010cc1 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000001 R10: ffffffff81bb4686 R11: 0000000000000001 R12: ffffffff902c1960 R13: 0000000000000033 R14: 0000000000000000 R15: ffff88804cf64a30 FS: 0000000000000000(0000) GS:ffff88802cd00000(0063) knlGS:00000000f44b4b40 CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 CR2: 000000002c921000 CR3: 000000004f507000 CR4: 0000000000150ee0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> alloc_pages+0x1a7/0x300 mm/mempolicy.c:2191 __get_free_pages+0x8/0x40 mm/page_alloc.c:5418 raw_cmd_copyin drivers/block/floppy.c:3113 [inline] raw_cmd_ioctl drivers/block/floppy.c:3160 [inline] fd_locked_ioctl+0x12e5/0x2820 drivers/block/floppy.c:3528 fd_ioctl drivers/block/floppy.c:3555 [inline] fd_compat_ioctl+0x891/0x1b60 drivers/block/floppy.c:3869 compat_blkdev_ioctl+0x3b8/0x810 block/ioctl.c:662 __do_compat_sys_ioctl+0x1c7/0x290 fs/ioctl.c:972 do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline] __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178 do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c Reported-by: syzbot+23a02c7df2cf2bc93fa2@xxxxxxxxxxxxxxxxxxxxxxxxx Link: https://lore.kernel.org/r/20211116131033.27685-1-sxwjean@xxxxxx Signed-off-by: Xiongwei Song <sxwjean@xxxxxxxxx> Signed-off-by: Denis Efremov <efremov@xxxxxxxxx> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/block/floppy.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c index fb2aafabfebc1..37ad3a2c442b1 100644 --- a/drivers/block/floppy.c +++ b/drivers/block/floppy.c @@ -3080,6 +3080,8 @@ static void raw_cmd_free(struct floppy_raw_cmd **ptr) } } +#define MAX_LEN (1UL << MAX_ORDER << PAGE_SHIFT) + static int raw_cmd_copyin(int cmd, void __user *param, struct floppy_raw_cmd **rcmd) { @@ -3107,7 +3109,7 @@ static int raw_cmd_copyin(int cmd, void __user *param, ptr->resultcode = 0; if (ptr->flags & (FD_RAW_READ | FD_RAW_WRITE)) { - if (ptr->length <= 0) + if (ptr->length <= 0 || ptr->length >= MAX_LEN) return -EINVAL; ptr->kernel_data = (char *)fd_dma_mem_alloc(ptr->length); fallback_on_nodma_alloc(&ptr->kernel_data, ptr->length); -- 2.34.1
