Revision d6e621de1fceb3b098ebf435ef7ea91ec4838a1a authored by Phillip Lougher on 15 May 2021, 00:27:16 UTC, committed by Linus Torvalds on 15 May 2021, 02:41:32 UTC
Sysbot has reported a "divide error" which has been identified as being caused by a corrupted file_size value within the file inode. This value has been corrupted to a much larger value than expected. Calculate_skip() is passed i_size_read(inode) >> msblk->block_log. Due to the file_size value corruption this overflows the int argument/variable in that function, leading to the divide error. This patch changes the function to use u64. This will accommodate any unexpectedly large values due to corruption. The value returned from calculate_skip() is clamped to be never more than SQUASHFS_CACHED_BLKS - 1, or 7. So file_size corruption does not lead to an unexpectedly large return result here. Link: https://lkml.kernel.org/r/20210507152618.9447-1-phillip@squashfs.org.uk Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk> Reported-by: <syzbot+e8f781243ce16ac2f962@syzkaller.appspotmail.com> Reported-by: <syzbot+7b98870d4fec9447b951@syzkaller.appspotmail.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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decode_stacktrace.sh
#!/bin/bash
# SPDX-License-Identifier: GPL-2.0
# (c) 2014, Sasha Levin <sasha.levin@oracle.com>
#set -x
if [[ $# < 1 ]]; then
echo "Usage:"
echo " $0 -r <release> | <vmlinux> [base path] [modules path]"
exit 1
fi
if [[ $1 == "-r" ]] ; then
vmlinux=""
basepath="auto"
modpath=""
release=$2
for fn in {,/usr/lib/debug}/boot/vmlinux-$release{,.debug} /lib/modules/$release{,/build}/vmlinux ; do
if [ -e "$fn" ] ; then
vmlinux=$fn
break
fi
done
if [[ $vmlinux == "" ]] ; then
echo "ERROR! vmlinux image for release $release is not found" >&2
exit 2
fi
else
vmlinux=$1
basepath=${2-auto}
modpath=$3
release=""
fi
declare -A cache
declare -A modcache
find_module() {
if [[ "$modpath" != "" ]] ; then
for fn in $(find "$modpath" -name "${module//_/[-_]}.ko*") ; do
if readelf -WS "$fn" | grep -qwF .debug_line ; then
echo $fn
return
fi
done
return 1
fi
modpath=$(dirname "$vmlinux")
find_module && return
if [[ $release == "" ]] ; then
release=$(gdb -ex 'print init_uts_ns.name.release' -ex 'quit' -quiet -batch "$vmlinux" | sed -n 's/\$1 = "\(.*\)".*/\1/p')
fi
for dn in {/usr/lib/debug,}/lib/modules/$release ; do
if [ -e "$dn" ] ; then
modpath="$dn"
find_module && return
fi
done
modpath=""
return 1
}
parse_symbol() {
# The structure of symbol at this point is:
# ([name]+[offset]/[total length])
#
# For example:
# do_basic_setup+0x9c/0xbf
if [[ $module == "" ]] ; then
local objfile=$vmlinux
elif [[ "${modcache[$module]+isset}" == "isset" ]]; then
local objfile=${modcache[$module]}
else
local objfile=$(find_module)
if [[ $objfile == "" ]] ; then
echo "WARNING! Modules path isn't set, but is needed to parse this symbol" >&2
return
fi
modcache[$module]=$objfile
fi
# Remove the englobing parenthesis
symbol=${symbol#\(}
symbol=${symbol%\)}
# Strip segment
local segment
if [[ $symbol == *:* ]] ; then
segment=${symbol%%:*}:
symbol=${symbol#*:}
fi
# Strip the symbol name so that we could look it up
local name=${symbol%+*}
# Use 'nm vmlinux' to figure out the base address of said symbol.
# It's actually faster to call it every time than to load it
# all into bash.
if [[ "${cache[$module,$name]+isset}" == "isset" ]]; then
local base_addr=${cache[$module,$name]}
else
local base_addr=$(nm "$objfile" | awk '$3 == "'$name'" && ($2 == "t" || $2 == "T") {print $1; exit}')
if [[ $base_addr == "" ]] ; then
# address not found
return
fi
cache[$module,$name]="$base_addr"
fi
# Let's start doing the math to get the exact address into the
# symbol. First, strip out the symbol total length.
local expr=${symbol%/*}
# Now, replace the symbol name with the base address we found
# before.
expr=${expr/$name/0x$base_addr}
# Evaluate it to find the actual address
expr=$((expr))
local address=$(printf "%x\n" "$expr")
# Pass it to addr2line to get filename and line number
# Could get more than one result
if [[ "${cache[$module,$address]+isset}" == "isset" ]]; then
local code=${cache[$module,$address]}
else
local code=$(${CROSS_COMPILE}addr2line -i -e "$objfile" "$address")
cache[$module,$address]=$code
fi
# addr2line doesn't return a proper error code if it fails, so
# we detect it using the value it prints so that we could preserve
# the offset/size into the function and bail out
if [[ $code == "??:0" ]]; then
return
fi
# Strip out the base of the path on each line
code=$(while read -r line; do echo "${line#$basepath/}"; done <<< "$code")
# In the case of inlines, move everything to same line
code=${code//$'\n'/' '}
# Replace old address with pretty line numbers
symbol="$segment$name ($code)"
}
decode_code() {
local scripts=`dirname "${BASH_SOURCE[0]}"`
echo "$1" | $scripts/decodecode
}
handle_line() {
local words
# Tokenize
read -a words <<<"$1"
# Remove hex numbers. Do it ourselves until it happens in the
# kernel
# We need to know the index of the last element before we
# remove elements because arrays are sparse
local last=$(( ${#words[@]} - 1 ))
for i in "${!words[@]}"; do
# Remove the address
if [[ ${words[$i]} =~ \[\<([^]]+)\>\] ]]; then
unset words[$i]
fi
# Format timestamps with tabs
if [[ ${words[$i]} == \[ && ${words[$i+1]} == *\] ]]; then
unset words[$i]
words[$i+1]=$(printf "[%13s\n" "${words[$i+1]}")
fi
done
if [[ ${words[$last]} =~ \[([^]]+)\] ]]; then
module=${words[$last]}
module=${module#\[}
module=${module%\]}
symbol=${words[$last-1]}
unset words[$last-1]
else
# The symbol is the last element, process it
symbol=${words[$last]}
module=
fi
unset words[$last]
parse_symbol # modifies $symbol
# Add up the line number to the symbol
echo "${words[@]}" "$symbol $module"
}
if [[ $basepath == "auto" ]] ; then
module=""
symbol="kernel_init+0x0/0x0"
parse_symbol
basepath=${symbol#kernel_init (}
basepath=${basepath%/init/main.c:*)}
fi
while read line; do
# Let's see if we have an address in the line
if [[ $line =~ \[\<([^]]+)\>\] ]] ||
[[ $line =~ [^+\ ]+\+0x[0-9a-f]+/0x[0-9a-f]+ ]]; then
# Translate address to line numbers
handle_line "$line"
# Is it a code line?
elif [[ $line == *Code:* ]]; then
decode_code "$line"
else
# Nothing special in this line, show it as is
echo "$line"
fi
done
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