From: Greg Kroah-Hartman Date: Sun, 28 Nov 2021 13:01:45 +0000 (+0100) Subject: 5.4-stable patches X-Git-Tag: v5.15.6~53 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=63843d1716a8911960eb51fa6e510fd941e76948;p=thirdparty%2Fkernel%2Fstable-queue.git 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 index 00000000000..7701351db61 --- /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 +Date: Fri, 19 Nov 2021 16:43:58 -0800 +Subject: proc/vmcore: fix clearing user buffer by properly using clear_user() + +From: David Hildenbrand + +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 +Acked-by: Baoquan He +Cc: Dave Young +Cc: Baoquan He +Cc: Vivek Goyal +Cc: Philipp Rudo +Cc: +Signed-off-by: Andrew Morton +Signed-off-by: Linus Torvalds +Signed-off-by: David Hildenbrand +Signed-off-by: Greg Kroah-Hartman +--- + 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 feb0292a13b..633d185c3b3 100644 --- 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