--- /dev/null
+From 48b71a9e66c2eab60564b1b1c85f4928ed04e406 Mon Sep 17 00:00:00 2001
+From: Lin Ma <linma@zju.edu.cn>
+Date: Tue, 16 Nov 2021 23:27:32 +0800
+Subject: NFC: add NCI_UNREG flag to eliminate the race
+
+From: Lin Ma <linma@zju.edu.cn>
+
+commit 48b71a9e66c2eab60564b1b1c85f4928ed04e406 upstream.
+
+There are two sites that calls queue_work() after the
+destroy_workqueue() and lead to possible UAF.
+
+The first site is nci_send_cmd(), which can happen after the
+nci_close_device as below
+
+nfcmrvl_nci_unregister_dev | nfc_genl_dev_up
+ nci_close_device |
+ flush_workqueue |
+ del_timer_sync |
+ nci_unregister_device | nfc_get_device
+ destroy_workqueue | nfc_dev_up
+ nfc_unregister_device | nci_dev_up
+ device_del | nci_open_device
+ | __nci_request
+ | nci_send_cmd
+ | queue_work !!!
+
+Another site is nci_cmd_timer, awaked by the nci_cmd_work from the
+nci_send_cmd.
+
+ ... | ...
+ nci_unregister_device | queue_work
+ destroy_workqueue |
+ nfc_unregister_device | ...
+ device_del | nci_cmd_work
+ | mod_timer
+ | ...
+ | nci_cmd_timer
+ | queue_work !!!
+
+For the above two UAF, the root cause is that the nfc_dev_up can race
+between the nci_unregister_device routine. Therefore, this patch
+introduce NCI_UNREG flag to easily eliminate the possible race. In
+addition, the mutex_lock in nci_close_device can act as a barrier.
+
+Signed-off-by: Lin Ma <linma@zju.edu.cn>
+Fixes: 6a2968aaf50c ("NFC: basic NCI protocol implementation")
+Reviewed-by: Jakub Kicinski <kuba@kernel.org>
+Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
+Link: https://lore.kernel.org/r/20211116152732.19238-1-linma@zju.edu.cn
+Signed-off-by: Jakub Kicinski <kuba@kernel.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ include/net/nfc/nci_core.h | 1 +
+ net/nfc/nci/core.c | 19 +++++++++++++++++--
+ 2 files changed, 18 insertions(+), 2 deletions(-)
+
+--- a/include/net/nfc/nci_core.h
++++ b/include/net/nfc/nci_core.h
+@@ -42,6 +42,7 @@ enum nci_flag {
+ NCI_UP,
+ NCI_DATA_EXCHANGE,
+ NCI_DATA_EXCHANGE_TO,
++ NCI_UNREG,
+ };
+
+ /* NCI device states */
+--- a/net/nfc/nci/core.c
++++ b/net/nfc/nci/core.c
+@@ -401,6 +401,11 @@ static int nci_open_device(struct nci_de
+
+ mutex_lock(&ndev->req_lock);
+
++ if (test_bit(NCI_UNREG, &ndev->flags)) {
++ rc = -ENODEV;
++ goto done;
++ }
++
+ if (test_bit(NCI_UP, &ndev->flags)) {
+ rc = -EALREADY;
+ goto done;
+@@ -464,6 +469,10 @@ done:
+ static int nci_close_device(struct nci_dev *ndev)
+ {
+ nci_req_cancel(ndev, ENODEV);
++
++ /* This mutex needs to be held as a barrier for
++ * caller nci_unregister_device
++ */
+ mutex_lock(&ndev->req_lock);
+
+ if (!test_and_clear_bit(NCI_UP, &ndev->flags)) {
+@@ -501,8 +510,8 @@ static int nci_close_device(struct nci_d
+ /* Flush cmd wq */
+ flush_workqueue(ndev->cmd_wq);
+
+- /* Clear flags */
+- ndev->flags = 0;
++ /* Clear flags except NCI_UNREG */
++ ndev->flags &= BIT(NCI_UNREG);
+
+ mutex_unlock(&ndev->req_lock);
+
+@@ -1182,6 +1191,12 @@ void nci_unregister_device(struct nci_de
+ {
+ struct nci_conn_info *conn_info, *n;
+
++ /* This set_bit is not protected with specialized barrier,
++ * However, it is fine because the mutex_lock(&ndev->req_lock);
++ * in nci_close_device() will help to emit one.
++ */
++ set_bit(NCI_UNREG, &ndev->flags);
++
+ nci_close_device(ndev);
+
+ destroy_workqueue(ndev->cmd_wq);
--- /dev/null
+From c1e63117711977cc4295b2ce73de29dd17066c82 Mon Sep 17 00:00:00 2001
+From: David Hildenbrand <david@redhat.com>
+Date: Fri, 19 Nov 2021 16:43:58 -0800
+Subject: proc/vmcore: fix clearing user buffer by properly using clear_user()
+
+From: David Hildenbrand <david@redhat.com>
+
+commit c1e63117711977cc4295b2ce73de29dd17066c82 upstream.
+
+To clear a user buffer we cannot simply use memset, we have to use
+clear_user(). With a virtio-mem device that registers a vmcore_cb and
+has some logically unplugged memory inside an added Linux memory block,
+I can easily trigger a BUG by copying the vmcore via "cp":
+
+ systemd[1]: Starting Kdump Vmcore Save Service...
+ kdump[420]: Kdump is using the default log level(3).
+ kdump[453]: saving to /sysroot/var/crash/127.0.0.1-2021-11-11-14:59:22/
+ kdump[458]: saving vmcore-dmesg.txt to /sysroot/var/crash/127.0.0.1-2021-11-11-14:59:22/
+ kdump[465]: saving vmcore-dmesg.txt complete
+ kdump[467]: saving vmcore
+ BUG: unable to handle page fault for address: 00007f2374e01000
+ #PF: supervisor write access in kernel mode
+ #PF: error_code(0x0003) - permissions violation
+ PGD 7a523067 P4D 7a523067 PUD 7a528067 PMD 7a525067 PTE 800000007048f867
+ Oops: 0003 [#1] PREEMPT SMP NOPTI
+ CPU: 0 PID: 468 Comm: cp Not tainted 5.15.0+ #6
+ Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.14.0-27-g64f37cc530f1-prebuilt.qemu.org 04/01/2014
+ RIP: 0010:read_from_oldmem.part.0.cold+0x1d/0x86
+ Code: ff ff ff e8 05 ff fe ff e9 b9 e9 7f ff 48 89 de 48 c7 c7 38 3b 60 82 e8 f1 fe fe ff 83 fd 08 72 3c 49 8d 7d 08 4c 89 e9 89 e8 <49> c7 45 00 00 00 00 00 49 c7 44 05 f8 00 00 00 00 48 83 e7 f81
+ RSP: 0018:ffffc9000073be08 EFLAGS: 00010212
+ RAX: 0000000000001000 RBX: 00000000002fd000 RCX: 00007f2374e01000
+ RDX: 0000000000000001 RSI: 00000000ffffdfff RDI: 00007f2374e01008
+ RBP: 0000000000001000 R08: 0000000000000000 R09: ffffc9000073bc50
+ R10: ffffc9000073bc48 R11: ffffffff829461a8 R12: 000000000000f000
+ R13: 00007f2374e01000 R14: 0000000000000000 R15: ffff88807bd421e8
+ FS: 00007f2374e12140(0000) GS:ffff88807f000000(0000) knlGS:0000000000000000
+ CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
+ CR2: 00007f2374e01000 CR3: 000000007a4aa000 CR4: 0000000000350eb0
+ Call Trace:
+ read_vmcore+0x236/0x2c0
+ proc_reg_read+0x55/0xa0
+ vfs_read+0x95/0x190
+ ksys_read+0x4f/0xc0
+ do_syscall_64+0x3b/0x90
+ entry_SYSCALL_64_after_hwframe+0x44/0xae
+
+Some x86-64 CPUs have a CPU feature called "Supervisor Mode Access
+Prevention (SMAP)", which is used to detect wrong access from the kernel
+to user buffers like this: SMAP triggers a permissions violation on
+wrong access. In the x86-64 variant of clear_user(), SMAP is properly
+handled via clac()+stac().
+
+To fix, properly use clear_user() when we're dealing with a user buffer.
+
+Link: https://lkml.kernel.org/r/20211112092750.6921-1-david@redhat.com
+Fixes: 997c136f518c ("fs/proc/vmcore.c: add hook to read_from_oldmem() to check for non-ram pages")
+Signed-off-by: David Hildenbrand <david@redhat.com>
+Acked-by: Baoquan He <bhe@redhat.com>
+Cc: Dave Young <dyoung@redhat.com>
+Cc: Baoquan He <bhe@redhat.com>
+Cc: Vivek Goyal <vgoyal@redhat.com>
+Cc: Philipp Rudo <prudo@redhat.com>
+Cc: <stable@vger.kernel.org>
+Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ fs/proc/vmcore.c | 15 ++++++++++-----
+ 1 file changed, 10 insertions(+), 5 deletions(-)
+
+--- a/fs/proc/vmcore.c
++++ b/fs/proc/vmcore.c
+@@ -105,14 +105,19 @@ static ssize_t read_from_oldmem(char *bu
+ nr_bytes = count;
+
+ /* If pfn is not ram, return zeros for sparse dump files */
+- if (pfn_is_ram(pfn) == 0)
+- memset(buf, 0, nr_bytes);
+- else {
++ if (pfn_is_ram(pfn) == 0) {
++ tmp = 0;
++ if (!userbuf)
++ memset(buf, 0, nr_bytes);
++ else if (clear_user(buf, nr_bytes))
++ tmp = -EFAULT;
++ } else {
+ tmp = copy_oldmem_page(pfn, buf, nr_bytes,
+ offset, userbuf);
+- if (tmp < 0)
+- return tmp;
+ }
++ if (tmp < 0)
++ return tmp;
++
+ *ppos += nr_bytes;
+ count -= nr_bytes;
+ buf += nr_bytes;
tcp_cubic-fix-spurious-hystart-ack-train-detections-.patch
tracing-check-pid-filtering-when-creating-events.patch
hugetlbfs-flush-tlbs-correctly-after-huge_pmd_unshare.patch
+proc-vmcore-fix-clearing-user-buffer-by-properly-using-clear_user.patch
+nfc-add-nci_unreg-flag-to-eliminate-the-race.patch
projects / thirdparty / kernel / stable-queue.git / commitdiff
