This is a note to let you know that I've just added the patch titled
iommufd: Fix unpinning of pages when an access is present
to the 6.2-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
iommufd-fix-unpinning-of-pages-when-an-access-is-present.patch
and it can be found in the queue-6.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 727c28c1cef2bc013d2c8bb6c50e410a3882a04e Mon Sep 17 00:00:00 2001
From: Jason Gunthorpe <jgg@xxxxxxxxxx>
Date: Fri, 31 Mar 2023 12:32:25 -0300
Subject: iommufd: Fix unpinning of pages when an access is present
From: Jason Gunthorpe <jgg@xxxxxxxxxx>
commit 727c28c1cef2bc013d2c8bb6c50e410a3882a04e upstream.
syzkaller found that the calculation of batch_last_index should use
'start_index' since at input to this function the batch is either empty or
it has already been adjusted to cross any accesses so it will start at the
point we are unmapping from.
Getting this wrong causes the unmap to run over the end of the pages
which corrupts pages that were never mapped. In most cases this triggers
the num pinned debugging:
WARNING: CPU: 0 PID: 557 at drivers/iommu/iommufd/pages.c:294 __iopt_area_unfill_domain+0x152/0x560
Modules linked in:
CPU: 0 PID: 557 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:__iopt_area_unfill_domain+0x152/0x560
Code: d2 0f ff 44 8b 64 24 54 48 8b 44 24 48 31 ff 44 89 e6 48 89 44 24 38 e8 fc d3 0f ff 45 85 e4 0f 85 eb 01 00 00 e8 0e d2 0f ff <0f> 0b e8 07 d2 0f ff 48 8b 44 24 38 89 5c 24 58 89 18 8b 44 24 54
RSP: 0018:ffffc9000108baf0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 00000000ffffffff RCX: ffffffff821e3f85
RDX: 0000000000000000 RSI: ffff88800faf0000 RDI: 0000000000000002
RBP: ffffc9000108bd18 R08: 000000000003ca25 R09: 0000000000000014
R10: 000000000003ca00 R11: 0000000000000024 R12: 0000000000000004
R13: 0000000000000801 R14: 00000000000007ff R15: 0000000000000800
FS: 00007f3499ce1740(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000243 CR3: 00000000179c2001 CR4: 0000000000770ef0
PKRU: 55555554
Call Trace:
<TASK>
iopt_area_unfill_domain+0x32/0x40
iopt_table_remove_domain+0x23f/0x4c0
iommufd_device_selftest_detach+0x3a/0x90
iommufd_selftest_destroy+0x55/0x70
iommufd_object_destroy_user+0xce/0x130
iommufd_destroy+0xa2/0xc0
iommufd_fops_ioctl+0x206/0x330
__x64_sys_ioctl+0x10e/0x160
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x72/0xdc
Also add some useful WARN_ON sanity checks.
Cc: <stable@xxxxxxxxxxxxxxx>
Fixes: 8d160cd4d506 ("iommufd: Algorithms for PFN storage")
Link: https://lore.kernel.org/r/2-v1-ceab6a4d7d7a+94-iommufd_syz_jgg@xxxxxxxxxx
Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
Reported-by: Pengfei Xu <pengfei.xu@xxxxxxxxx>
Tested-by: Pengfei Xu <pengfei.xu@xxxxxxxxx>
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/iommu/iommufd/pages.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
--- a/drivers/iommu/iommufd/pages.c
+++ b/drivers/iommu/iommufd/pages.c
@@ -1205,13 +1205,21 @@ iopt_area_unpin_domain(struct pfn_batch
unsigned long start =
max(start_index, *unmapped_end_index);
+ if (IS_ENABLED(CONFIG_IOMMUFD_TEST) &&
+ batch->total_pfns)
+ WARN_ON(*unmapped_end_index -
+ batch->total_pfns !=
+ start_index);
batch_from_domain(batch, domain, area, start,
last_index);
- batch_last_index = start + batch->total_pfns - 1;
+ batch_last_index = start_index + batch->total_pfns - 1;
} else {
batch_last_index = last_index;
}
+ if (IS_ENABLED(CONFIG_IOMMUFD_TEST))
+ WARN_ON(batch_last_index > real_last_index);
+
/*
* unmaps must always 'cut' at a place where the pfns are not
* contiguous to pair with the maps that always install
Patches currently in stable-queue which might be from jgg@xxxxxxxxxx are
queue-6.2/fsdax-unshare-zero-destination-if-srcmap-is-hole-or-unwritten.patch
queue-6.2/iommufd-do-not-corrupt-the-pfn-list-when-doing-batch-carry.patch
queue-6.2/iommufd-check-for-uptr-overflow.patch
queue-6.2/iommufd-fix-unpinning-of-pages-when-an-access-is-present.patch
