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Martin KaFai Lau f30d4968e9 bpf: Do not reject when the stack read size is different from the tracked scalar size 
Below is a simplified case from a report in bcc [0]:

  r4 = 20
  *(u32 *)(r10 -4) = r4
  *(u32 *)(r10 -8) = r4  /* r4 state is tracked */
  r4 = *(u64 *)(r10 -8)  /* Read more than the tracked 32bit scalar.
			  * verifier rejects as 'corrupted spill memory'.
			  */

After commit 354e8f1970 ("bpf: Support <8-byte scalar spill and refill"),
the 8-byte aligned 32bit spill is also tracked by the verifier and the
register state is stored.

However, if 8 bytes are read from the stack instead of the tracked 4 byte
scalar, then verifier currently rejects the program as "corrupted spill
memory". This patch fixes this case by allowing it to read but marks the
register as unknown.

Also note that, if the prog is trying to corrupt/leak an earlier spilled
pointer by spilling another <8 bytes register on top, this has already
been rejected in the check_stack_write_fixed_off().

  [0] https://github.com/iovisor/bcc/pull/3683

Fixes: 354e8f1970 ("bpf: Support <8-byte scalar spill and refill")
Reported-by: Hengqi Chen <hengqi.chen@gmail.com>
Reported-by: Yonghong Song <yhs@gmail.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Hengqi Chen <hengqi.chen@gmail.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211102064535.316018-1-kafai@fb.com
2021-11-03 15:46:46 +01:00
arch - Do not #GP on userspace use of CLI/STI but pretend it was a NOP to 2021-11-02 07:56:47 -07:00
block for-5.16/inode-sync-2021-10-29 2021-11-01 10:25:27 -07:00
certs certs: Add support for using elliptic curve keys for signing modules 2021-08-23 19:55:42 +03:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2021-11-01 21:24:02 -07:00
Documentation security: add sctp_assoc_established hook 2021-11-03 11:09:20 +00:00
drivers net: dsa: felix: fix broken VLAN-tagged PTP under VLAN-aware bridge 2021-11-03 14:22:00 +00:00
fs libfs: Support RENAME_EXCHANGE in simple_rename() 2021-11-03 15:43:08 +01:00
include libfs: Move shmem_exchange to simple_rename_exchange 2021-11-03 15:43:00 +01:00
init Tracing updates for 5.16: 2021-11-01 20:05:19 -07:00
ipc ipc: remove memcg accounting for sops objects in do_semtimedop() 2021-09-14 10:22:11 -07:00
kernel bpf: Do not reject when the stack read size is different from the tracked scalar size 2021-11-03 15:46:46 +01:00
lib Core: 2021-11-02 06:20:58 -07:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm libfs: Move shmem_exchange to simple_rename_exchange 2021-11-03 15:43:00 +01:00
net net: dsa: felix: fix broken VLAN-tagged PTP under VLAN-aware bridge 2021-11-03 14:22:00 +00:00
samples Core: 2021-11-02 06:20:58 -07:00
scripts Core: 2021-11-02 06:20:58 -07:00
security security: implement sctp_assoc_established hook in selinux 2021-11-03 11:09:20 +00:00
sound ALSA: usb-audio: Fix microphone sound on Jieli webcam. 2021-10-19 08:07:01 +02:00
tools selftests/bpf: Make netcnt selftests serial to avoid spurious failures 2021-11-03 15:43:09 +01:00
usr .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
virt KVM: Remove tlbs_dirty 2021-09-23 11:01:12 -04:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap media updates for v5.16-rc1 2021-11-01 18:45:08 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: Update ENA maintainers information 2021-11-02 19:15:46 -07:00
Makefile Core: 2021-11-02 06:20:58 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.