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Jann Horn b10acd9858 romfs: fix uninitialized memory leak in romfs_dev_read()
commit bcf85fcedfdd17911982a3e3564fcfec7b01eebd 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: da4458bda237 ("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>
2021-03-16 16:34:28 +08:00
Documentation kbuild: support LLVM=1 to switch the default tools to Clang/LLVM 2021-03-16 16:34:25 +08:00
LICENSES Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
arch x86/boot: kbuild: allow readelf executable to be specified 2021-03-16 16:34:24 +08:00
block iocost: Fix check condition of iocg abs_vdebt 2021-03-16 16:33:18 +08:00
certs Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
crypto crypto: algif_aead - fix uninitialized ctx->init 2021-03-16 16:34:22 +08:00
drivers spi: Prevent adding devices below an unregistering controller 2021-03-16 16:34:28 +08:00
fs romfs: fix uninitialized memory leak in romfs_dev_read() 2021-03-16 16:34:28 +08:00
include iommu/vt-d: Enforce PASID devTLB field mask 2021-03-16 16:34:16 +08:00
init x86: Fix early boot crash on gcc-10, third try 2021-03-16 16:28:02 +08:00
ipc ipc/util.c: sysvipc_find_ipc() incorrectly updates position index 2021-03-16 16:27:51 +08:00
kernel module: Correctly truncate sysfs sections output 2021-03-16 16:34:09 +08:00
lib test_kmod: avoid potential double free in trigger_config_run_type() 2021-03-16 16:34:21 +08:00
mm khugepaged: adjust VM_BUG_ON_MM() in __khugepaged_enter() 2021-03-16 16:34:26 +08:00
net can: j1939: socket: j1939_sk_bind(): make sure ml_priv is allocated 2021-03-16 16:34:28 +08:00
package config/arm64: OPEN CONFIG_PSI and phytium configs 2021-03-16 11:02:59 +08:00
samples bpf: Fix fds_example SIGSEGV error 2021-03-16 16:33:24 +08:00
scripts recordmcount: Fix build failure on non arm64 2021-03-16 16:34:19 +08:00
security Smack: prevent underflow in smk_set_cipso() 2021-03-16 16:33:40 +08:00
sound ALSA: hda/realtek: Add quirk for Samsung Galaxy Book Ion 2021-03-16 16:34:27 +08:00
tools perf probe: Fix memory leakage when the probe point is not found 2021-03-16 16:34:26 +08:00
usr Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
virt KVM: arm64: Don't inherit exec permission across page-table levels 2021-03-16 16:32:57 +08:00
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MAINTAINERS Documentation/llvm: add documentation on building w/ Clang/LLVM 2021-03-16 16:34:24 +08:00
Makefile kbuild: support LLVM=1 to switch the default tools to Clang/LLVM 2021-03-16 16:34:25 +08:00
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Tencent Linux Kernel 4.0