syzkaller found that setting up a map with a user VA that wraps past zero
can trigger WARN_ONs, particularly from pin_user_pages weirdly returning 0
due to invalid arguments.
Prevent creating a pages with a uptr and size that would math overflow.
WARNING: CPU: 0 PID: 518 at drivers/iommu/iommufd/pages.c:793 pfn_reader_user_pin+0x2e6/0x390
Modules linked in:
CPU: 0 PID: 518 Comm: repro Not tainted 6.3.0-rc2-eeac8ede1755+ #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
RIP: 0010:pfn_reader_user_pin+0x2e6/0x390
Code: b1 11 e9 25 fe ff ff e8 28 e4 0f ff 31 ff 48 89 de e8 2e e6 0f ff 48 85 db 74 0a e8 14 e4 0f ff e9 4d ff ff ff e8 0a e4 0f ff <0f> 0b bb f2 ff ff ff e9 3c ff ff ff e8 f9 e3 0f ff ba 01 00 00 00
RSP: 0018:ffffc90000f9fa30 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff821e2b72
RDX: 0000000000000000 RSI: ffff888014184680 RDI: 0000000000000002
RBP: ffffc90000f9fa78 R08: 00000000000000ff R09: 0000000079de6f4e
R10: ffffc90000f9f790 R11: ffff888014185418 R12: ffffc90000f9fc60
R13: 0000000000000002 R14: ffff888007879800 R15: 0000000000000000
FS: 00007f4227555740(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000043 CR3: 000000000e748005 CR4: 0000000000770ef0
PKRU: 55555554
Call Trace:
<TASK>
pfn_reader_next+0x14a/0x7b0
? interval_tree_double_span_iter_update+0x11a/0x140
pfn_reader_first+0x140/0x1b0
iopt_pages_rw_slow+0x71/0x280
? __this_cpu_preempt_check+0x20/0x30
iopt_pages_rw_access+0x2b2/0x5b0
iommufd_access_rw+0x19f/0x2f0
iommufd_test+0xd11/0x16f0
? write_comp_data+0x2f/0x90
iommufd_fops_ioctl+0x206/0x330
__x64_sys_ioctl+0x10e/0x160
? __pfx_iommufd_fops_ioctl+0x10/0x10
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x72/0xdc
Cc: <stable@xxxxxxxxxxxxxxx>
Fixes: 8d160cd4d506 ("iommufd: Algorithms for PFN storage")
Reported-by: Pengfei Xu <pengfei.xu@xxxxxxxxx>
Link: https://lore.kernel.org/r/ZA/O6vGUfni158oK@xxxxxxxxxxxxxxxx
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
---
drivers/iommu/iommufd/pages.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/iommu/iommufd/pages.c b/drivers/iommu/iommufd/pages.c
index f8d92c9bb65b60..400ec7c91ed7e7 100644
--- a/drivers/iommu/iommufd/pages.c
+++ b/drivers/iommu/iommufd/pages.c
@@ -1142,6 +1142,7 @@ struct iopt_pages *iopt_alloc_pages(void __user *uptr, unsigned long length,
bool writable)
{
struct iopt_pages *pages;
+ unsigned long end;
/*
* The iommu API uses size_t as the length, and protect the DIV_ROUND_UP
@@ -1150,6 +1151,9 @@ struct iopt_pages *iopt_alloc_pages(void __user *uptr, unsigned long length,
if (length > SIZE_MAX - PAGE_SIZE || length == 0)
return ERR_PTR(-EINVAL);
+ if (check_add_overflow((unsigned long)uptr, length, &end))
+ return ERR_PTR(-EOVERFLOW);
+
pages = kzalloc(sizeof(*pages), GFP_KERNEL_ACCOUNT);
if (!pages)
return ERR_PTR(-ENOMEM);
--
2.40.0
