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Jann Horn 19a77c937a romfs: fix uninitialized memory leak in romfs_dev_read()
commit bcf85fcedf upstream.

romfs has a superblock field that limits the size of the filesystem; data
beyond that limit is never accessed.

romfs_dev_read() fetches a caller-supplied number of bytes from the
backing device.  It returns 0 on success or an error code on failure;
therefore, its API can't represent short reads, it's all-or-nothing.

However, when romfs_dev_read() detects that the requested operation would
cross the filesystem size limit, it currently silently truncates the
requested number of bytes.  This e.g.  means that when the content of a
file with size 0x1000 starts one byte before the filesystem size limit,
->readpage() will only fill a single byte of the supplied page while
leaving the rest uninitialized, leaking that uninitialized memory to
userspace.

Fix it by returning an error code instead of truncating the read when the
requested read operation would go beyond the end of the filesystem.

Fixes: da4458bda2 ("NOMMU: Make it possible for RomFS to use MTD devices directly")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: David Howells <dhowells@redhat.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200818013202.2246365-1-jannh@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-08-26 10:40:51 +02:00
Documentation kbuild: support LLVM=1 to switch the default tools to Clang/LLVM 2020-08-26 10:40:47 +02:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
arch x86/boot: kbuild: allow readelf executable to be specified 2020-08-26 10:40:46 +02:00
block iocost: Fix check condition of iocg abs_vdebt 2020-08-19 08:15:58 +02:00
certs PKCS#7: Refactor verify_pkcs7_signature() 2019-08-05 18:40:18 -04:00
crypto crypto: algif_aead - fix uninitialized ctx->init 2020-08-21 13:05:38 +02:00
drivers spi: Prevent adding devices below an unregistering controller 2020-08-26 10:40:50 +02:00
fs romfs: fix uninitialized memory leak in romfs_dev_read() 2020-08-26 10:40:51 +02:00
include iommu/vt-d: Enforce PASID devTLB field mask 2020-08-21 13:05:34 +02:00
init x86: Fix early boot crash on gcc-10, third try 2020-05-20 08:20:34 +02:00
ipc ipc/util.c: sysvipc_find_ipc() incorrectly updates position index 2020-05-20 08:20:16 +02:00
kernel module: Correctly truncate sysfs sections output 2020-08-21 13:05:28 +02:00
lib test_kmod: avoid potential double free in trigger_config_run_type() 2020-08-21 13:05:37 +02:00
mm khugepaged: adjust VM_BUG_ON_MM() in __khugepaged_enter() 2020-08-26 10:40:48 +02:00
net can: j1939: socket: j1939_sk_bind(): make sure ml_priv is allocated 2020-08-26 10:40:50 +02:00
samples bpf: Fix fds_example SIGSEGV error 2020-08-19 08:16:03 +02:00
scripts recordmcount: Fix build failure on non arm64 2020-08-21 13:05:36 +02:00
security Smack: prevent underflow in smk_set_cipso() 2020-08-19 08:16:16 +02:00
sound ALSA: hda/realtek: Add quirk for Samsung Galaxy Book Ion 2020-08-26 10:40:50 +02:00
tools perf probe: Fix memory leakage when the probe point is not found 2020-08-26 10:40:48 +02:00
usr initramfs: restore default compression behavior 2020-04-08 09:08:38 +02:00
virt KVM: arm64: Don't inherit exec permission across page-table levels 2020-08-05 09:59:51 +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 kbuild: support LLVM=1 to switch the default tools to Clang/LLVM 2020-08-26 10:40:47 +02:00
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.