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Aleksandr Nogikh 4bffc9618c netem: fix zero division in tabledist
[ Upstream commit eadd1befdd778a1eca57fad058782bd22b4db804 ]

Currently it is possible to craft a special netlink RTM_NEWQDISC
command that can result in jitter being equal to 0x80000000. It is
enough to set the 32 bit jitter to 0x02000000 (it will later be
multiplied by 2^6) or just set the 64 bit jitter via
TCA_NETEM_JITTER64. This causes an overflow during the generation of
uniformly distributed numbers in tabledist(), which in turn leads to
division by zero (sigma != 0, but sigma * 2 is 0).

The related fragment of code needs 32-bit division - see commit
9b0ed89 ("netem: remove unnecessary 64 bit modulus"), so switching to
64 bit is not an option.

Fix the issue by keeping the value of jitter within the range that can
be adequately handled by tabledist() - [0;INT_MAX]. As negative std
deviation makes no sense, take the absolute value of the passed value
and cap it at INT_MAX. Inside tabledist(), switch to unsigned 32 bit
arithmetic in order to prevent overflows.

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Aleksandr Nogikh <nogikh@google.com>
Reported-by: syzbot+ec762a6342ad0d3c0d8f@syzkaller.appspotmail.com
Acked-by: Stephen Hemminger <stephen@networkplumber.org>
Link: https://lore.kernel.org/r/20201028170731.1383332-1-aleksandrnogikh@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-01 12:01:03 +01:00
arch x86/PCI: Fix intel_mid_pci.c build error when ACPI is not enabled 2020-11-01 12:01:02 +01:00
block block: ratelimit handle_bad_sector() message 2020-10-29 09:58:01 +01:00
certs PKCS#7: Refactor verify_pkcs7_signature() 2019-08-05 18:40:18 -04:00
crypto crypto: algif_skcipher - EBUSY on aio should be an error 2020-10-29 09:57:30 +01:00
Documentation x86/fpu: Allow multiple bits in clearcpuid= parameter 2020-10-29 09:57:29 +01:00
drivers mlxsw: core: Fix memory leak on module removal 2020-11-01 12:01:03 +01:00
fs efivarfs: Replace invalid slashes with exclamation marks in dentries. 2020-11-01 12:01:02 +01:00
include netfilter: nftables_offload: KASAN slab-out-of-bounds Read in nft_flow_rule_create 2020-11-01 12:01:01 +01:00
init kprobes: tracing/kprobes: Fix to kill kprobes on initmem after boot 2020-10-01 13:18:23 +02:00
ipc ipc/util.c: sysvipc_find_ipc() incorrectly updates position index 2020-05-20 08:20:16 +02:00
kernel bpf: Limit caller's stack depth 256 for subprogs with tailcalls 2020-10-29 09:58:06 +01:00
lib lib/crc32.c: fix trivial typo in preprocessor condition 2020-10-29 09:57:52 +01:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm mm/page_owner: change split_page_owner to take a count 2020-10-29 09:57:52 +01:00
net netem: fix zero division in tabledist 2020-11-01 12:01:03 +01:00
samples misc: vop: add round_up(x,4) for vring_size to avoid kernel panic 2020-10-29 09:58:04 +01:00
scripts scripts/setlocalversion: make git describe output more reliable 2020-11-01 12:01:01 +01:00
security ima: Don't ignore errors from crypto_shash_update() 2020-10-29 09:57:28 +01:00
sound ALSA: hda/ca0132 - Add new quirk ID for SoundBlaster AE-7. 2020-10-29 09:58:09 +01:00
tools objtool: Support Clang non-section symbols in ORC generation 2020-11-01 12:01:01 +01:00
usr initramfs: restore default compression behavior 2020-04-08 09:08:38 +02:00
virt KVM: arm64: Assume write fault on S1PTW permission fault on instruction fetch 2020-10-01 13:18:25 +02:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Modules updates for v5.4 2019-09-22 10:34:46 -07:00
.mailmap ARM: SoC fixes 2019-11-10 13:41:59 -08:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS MAINTAINERS: Remove Simon as Renesas SoC Co-Maintainer 2019-10-10 08:12:51 -07:00
Kbuild kbuild: do not descend to ./Kbuild when cleaning 2019-08-21 21:03:58 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS Documentation/llvm: add documentation on building w/ Clang/LLVM 2020-08-26 10:40:46 +02:00
Makefile Linux 5.4.73 2020-10-29 09:58:11 +01:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.