5.4-stable patches

added patches:
	proc-vmcore-fix-clearing-user-buffer-by-properly-using-clear_user.patch

diff --git a/queue-5.4/proc-vmcore-fix-clearing-user-buffer-by-properly-using-clear_user.patch b/queue-5.4/proc-vmcore-fix-clearing-user-buffer-by-properly-using-clear_user.patch
new file mode 100644 (file)
index 0000000..7701351
--- /dev/null
+++ b/queue-5.4/proc-vmcore-fix-clearing-user-buffer-by-properly-using-clear_user.patch
@@ -0,0 +1,104 @@
+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: David Hildenbrand <david@redhat.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ fs/proc/vmcore.c |   16 ++++++++++------
+ 1 file changed, 10 insertions(+), 6 deletions(-)
+
+--- a/fs/proc/vmcore.c
++++ b/fs/proc/vmcore.c
+@@ -125,9 +125,13 @@ ssize_t read_from_oldmem(char *buf, size
+                       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 {
+                       if (encrypted)
+                               tmp = copy_oldmem_page_encrypted(pfn, buf,
+                                                                nr_bytes,
+@@ -136,10 +140,10 @@ ssize_t read_from_oldmem(char *buf, size
+                       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;

diff --git a/queue-5.4/series b/queue-5.4/series
index feb0292a13b43151cd54888454ea30f5ba76d792..633d185c3b3a6327bc797e67a782d76aefd2f271 100644 (file)
--- a/queue-5.4/series
+++ b/queue-5.4/series
@@ -42,3 +42,4 @@ pci-aardvark-set-pci-bridge-class-code-to-pci-bridge.patch
 pci-aardvark-fix-support-for-pci_bridge_ctl_bus_reset-on-emulated-bridge.patch
 pinctrl-armada-37xx-correct-pwm-pins-definitions.patch
 arm64-dts-marvell-armada-37xx-set-pcie_reset_pin-to-gpio-function.patch
+proc-vmcore-fix-clearing-user-buffer-by-properly-using-clear_user.patch