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Filename Latest commit message Latest commit date
Josh Poimboeuf e28b19ca2a x86/unwind/orc: Disable KASAN checking in the ORC unwinder, part 2
commit e504e74cc3a2c092b05577ce3e8e013fae7d94e6 upstream.

KASAN reserves "redzone" areas between stack frames in order to detect
stack overruns.  A read or write to such an area triggers a KASAN
"stack-out-of-bounds" BUG.

Normally, the ORC unwinder stays in-bounds and doesn't access the
redzone.  But sometimes it can't find ORC metadata for a given
instruction.  This can happen for code which is missing ORC metadata, or
for generated code.  In such cases, the unwinder attempts to fall back
to frame pointers, as a best-effort type thing.

This fallback often works, but when it doesn't, the unwinder can get
confused and go off into the weeds into the KASAN redzone, triggering
the aforementioned KASAN BUG.

But in this case, the unwinder's confusion is actually harmless and
working as designed.  It already has checks in place to prevent
off-stack accesses, but those checks get short-circuited by the KASAN
BUG.  And a BUG is a lot more disruptive than a harmless unwinder
warning.

Disable the KASAN checks by using READ_ONCE_NOCHECK() for all stack
accesses.  This finishes the job started by commit 881125bfe6
("x86/unwind: Disable KASAN checking in the ORC unwinder"), which only
partially fixed the issue.

Fixes: ee9f8fce99 ("x86/unwind: Add the ORC unwinder")
Reported-by: Ivan Babrou <ivan@cloudflare.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Tested-by: Ivan Babrou <ivan@cloudflare.com>
Cc: stable@kernel.org
Link: https://lkml.kernel.org/r/9583327904ebbbeda399eca9c56d6c7085ac20fe.1612534649.git.jpoimboe@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-17 17:03:57 +01:00
arch x86/unwind/orc: Disable KASAN checking in the ORC unwinder, part 2 2021-03-17 17:03:57 +01:00
block blk-settings: align max_sectors on "logical_block_size" boundary 2021-03-04 10:26:40 +01:00
certs certs: Fix blacklist flag type confusion 2021-03-04 10:26:29 +01:00
crypto crypto: tcrypt - avoid signed overflow in byte count 2021-03-07 12:20:46 +01:00
Documentation sysfs: Add sysfs_emit and sysfs_emit_at to format sysfs output 2021-03-07 12:20:48 +01:00
drivers zram: fix return value on writeback_store 2021-03-17 17:03:57 +01:00
fs binfmt_misc: fix possible deadlock in bm_register_write 2021-03-17 17:03:57 +01:00
include include/linux/sched/mm.h: use rcu_dereference in in_vfork() 2021-03-17 17:03:56 +01:00
init fgraph: Initialize tracing_graph_pause at task creation 2021-02-10 09:25:29 +01:00
ipc
kernel sched/membarrier: fix missing local execution of ipi_sync_rq_state() 2021-03-17 17:03:57 +01:00
lib PCI: Fix pci_register_io_range() memory leak 2021-03-17 17:03:44 +01:00
LICENSES
mm Revert "mm, slub: consider rest of partial list if acquire_slab() fails" 2021-03-17 17:03:34 +01:00
net SUNRPC: Set memalloc_nofs_save() for sync tasks 2021-03-17 17:03:56 +01:00
samples samples, bpf: Add missing munmap in xdpsock 2021-03-17 17:03:33 +01:00
scripts ftrace: Have recordmcount use w8 to read relp->r_info in arm64_is_fake_mcount 2021-03-09 11:09:39 +01:00
security Revert 95ebabde382c ("capabilities: Don't allow writing ambiguous v3 file capabilities") 2021-03-17 17:03:47 +01:00
sound ALSA: usb-audio: Apply the control quirk to Plantronics headsets 2021-03-17 17:03:47 +01:00
tools perf traceevent: Ensure read cmdlines are null terminated. 2021-03-17 17:03:37 +01:00
usr
virt KVM: Use kvm_pfn_t for local PFN variable in hva_to_pfn_remapped() 2021-02-26 10:10:28 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS
Makefile kbuild: clamp SUBLEVEL to 255 2021-03-17 17:03:44 +01:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.