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Revision a57b70519d1f7c53be98478623652738e5ac70d5 authored by Liam Howlett on 18 October 2022, 19:17:12 UTC, committed by Andrew Morton on 21 October 2022, 04:27:23 UTC 
mm/mmap: fix MAP_FIXED address return on VMA merge
 
mmap should return the start address of newly mapped area when successful.
On a successful merge of a VMA, the return address was changed and thus
was violating that expectation from userspace.

This is a restoration of functionality provided by 309d08d9b3a3
(mm/mmap.c: fix mmap return value when vma is merged after call_mmap()). 
For completeness of fixing MAP_FIXED, implement the comments from the
previous discussion to never update the address and fail if the address
changes.  Leaving the error as a WARN_ON() to avoid crashing the kernel.

Link: https://lkml.kernel.org/r/20221018191613.4133459-1-Liam.Howlett@oracle.com
Link: https://lore.kernel.org/all/Y06yk66SKxlrwwfb@lakrids/
Link: https://lore.kernel.org/all/20201203085350.22624-1-liuzixian4@huawei.com/
Fixes: 4dd1b84140c1 ("mm/mmap: use advanced maple tree API for mmap_region()")
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reported-by: Mark Rutland <mark.rutland@arm.com>
Cc: Liu Zixian <liuzixian4@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
1 parent 1cd916d
Raw File
syscallnr.sh 
#!/bin/sh
# SPDX-License-Identifier: GPL-2.0-only
#
# Generate a syscall number header.
#
# Each line of the syscall table should have the following format:
#
# NR ABI NAME [NATIVE] [COMPAT]
#
# NR       syscall number
# ABI      ABI name
# NAME     syscall name
# NATIVE   native entry point (optional)
# COMPAT   compat entry point (optional)
set -e

usage() {
	echo >&2 "usage: $0 [--abis ABIS] [--prefix PREFIX] INFILE OUTFILE" >&2
	echo >&2
	echo >&2 "  INFILE    input syscall table"
	echo >&2 "  OUTFILE   output header file"
	echo >&2
	echo >&2 "options:"
	echo >&2 "  --abis ABIS        ABI(s) to handle (By default, all lines are handled)"
	echo >&2 "  --prefix PREFIX    The prefix to the macro like __NR_<PREFIX><NAME>"
	exit 1
}

# default unless specified by options
abis=
prefix=

while [ $# -gt 0 ]
do
	case $1 in
	--abis)
		abis=$(echo "($2)" | tr ',' '|')
		shift 2;;
	--prefix)
		prefix=$2
		shift 2;;
	-*)
		echo "$1: unknown option" >&2
		usage;;
	*)
		break;;
	esac
done

if [ $# -ne 2 ]; then
	usage
fi

infile="$1"
outfile="$2"

guard=_ASM_$(basename "$outfile" |
	sed -e 'y/abcdefghijklmnopqrstuvwxyz/ABCDEFGHIJKLMNOPQRSTUVWXYZ/' \
	-e 's/[^A-Z0-9_]/_/g' -e 's/__/_/g')

grep -E "^[0-9A-Fa-fXx]+[[:space:]]+$abis" "$infile" | sort -n | {
	echo "#ifndef $guard"
	echo "#define $guard"
	echo

	max=0
	while read nr abi name native compat ; do
		max=$nr
	done

	echo "#define __NR_${prefix}syscalls $(($max + 1))"
	echo
	echo "#endif /* $guard */"
} > "$outfile"
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