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Harshit Mogalapalli ad78c5047d VMCI: Fix memcpy() run-time warning in dg_dispatch_as_host()
[ Upstream commit 19b070fefd ]

Syzkaller hit 'WARNING in dg_dispatch_as_host' bug.

memcpy: detected field-spanning write (size 56) of single field "&dg_info->msg"
at drivers/misc/vmw_vmci/vmci_datagram.c:237 (size 24)

WARNING: CPU: 0 PID: 1555 at drivers/misc/vmw_vmci/vmci_datagram.c:237
dg_dispatch_as_host+0x88e/0xa60 drivers/misc/vmw_vmci/vmci_datagram.c:237

Some code commentry, based on my understanding:

544 #define VMCI_DG_SIZE(_dg) (VMCI_DG_HEADERSIZE + (size_t)(_dg)->payload_size)
/// This is 24 + payload_size

memcpy(&dg_info->msg, dg, dg_size);
	Destination = dg_info->msg ---> this is a 24 byte
					structure(struct vmci_datagram)
	Source = dg --> this is a 24 byte structure (struct vmci_datagram)
	Size = dg_size = 24 + payload_size

{payload_size = 56-24 =32} -- Syzkaller managed to set payload_size to 32.

 35 struct delayed_datagram_info {
 36         struct datagram_entry *entry;
 37         struct work_struct work;
 38         bool in_dg_host_queue;
 39         /* msg and msg_payload must be together. */
 40         struct vmci_datagram msg;
 41         u8 msg_payload[];
 42 };

So those extra bytes of payload are copied into msg_payload[], a run time
warning is seen while fuzzing with Syzkaller.

One possible way to fix the warning is to split the memcpy() into
two parts -- one -- direct assignment of msg and second taking care of payload.

Gustavo quoted:
"Under FORTIFY_SOURCE we should not copy data across multiple members
in a structure."

Reported-by: syzkaller <syzkaller@googlegroups.com>
Suggested-by: Vegard Nossum <vegard.nossum@oracle.com>
Suggested-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/20240105164001.2129796-2-harshit.m.mogalapalli@oracle.com
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-04-13 12:59:39 +02:00
arch x86/cpufeatures: Add CPUID_LNX_5 to track recently added Linux-defined word 2024-04-13 12:59:38 +02:00
block block: add check that partition length needs to be aligned with block size 2024-04-13 12:59:23 +02:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:13:17 +02:00
crypto crypto: api - Disallow identical driver names 2024-02-23 08:41:52 +01:00
Documentation x86/cpu: Enable STIBP on AMD if Automatic IBRS is enabled 2024-04-13 12:59:13 +02:00
drivers VMCI: Fix memcpy() run-time warning in dg_dispatch_as_host() 2024-04-13 12:59:39 +02:00
fs vboxsf: Avoid an spurious warning if load_nls_xxx() fails 2024-04-13 12:59:25 +02:00
include objtool: Add asm version of STACK_FRAME_NON_STANDARD 2024-04-13 12:59:39 +02:00
init init: open /initrd.image with O_LARGEFILE 2024-04-13 12:59:02 +02:00
io_uring io_uring: ensure '0' is returned on file registration success 2024-04-13 12:59:22 +02:00
ipc ipc/sem: Fix dangling sem_array access in semtimedop race 2022-12-08 11:24:00 +01:00
kernel bpf: Protect against int overflow for stack access size 2024-04-13 12:59:16 +02:00
lib net: blackhole_dev: fix build warning for ethh set but not used 2024-03-26 18:21:50 -04:00
LICENSES LICENSES/deprecated: add Zlib license text 2020-09-16 14:33:49 +02:00
mm mm, vmscan: prevent infinite loop for costly GFP_NOIO | __GFP_RETRY_MAYFAIL allocations 2024-04-13 12:59:22 +02:00
net mptcp: don't account accept() of non-MPC client as fallback to TCP 2024-04-13 12:59:38 +02:00
samples samples/hw_breakpoint: fix building without module unloading 2023-09-23 11:01:09 +02:00
scripts scripts: kernel-doc: Fix syntax error due to undeclared args variable 2024-04-13 12:58:46 +02:00
security smack: Handle SMACK64TRANSMUTE in smack_inode_setsecurity() 2024-04-13 12:58:00 +02:00
sound ALSA: hda/realtek: Update Panasonic CF-SZ6 quirk to support headset with microphone 2024-04-13 12:59:34 +02:00
tools objtool: Add asm version of STACK_FRAME_NON_STANDARD 2024-04-13 12:59:39 +02:00
usr usr/include/Makefile: add linux/nfc.h to the compile-test coverage 2022-02-01 17:25:48 +01:00
virt KVM: Always flush async #PF workqueue when vCPU is being destroyed 2024-04-13 12:58:04 +02:00
.clang-format RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore kbuild: generate Module.symvers only when vmlinux exists 2021-05-19 10:12:59 +02:00
.mailmap mailmap: add two more addresses of Uwe Kleine-König 2020-12-06 10:19:07 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Jason Cooper to CREDITS 2020-11-30 10:20:34 +01:00
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 Remove DECnet support from kernel 2023-06-21 15:45:38 +02:00
Makefile Linux 5.10.214 2024-03-26 18:23:07 -04:00
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
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    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
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the problems which may result by upgrading your kernel.