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fix: arm64: cve-2017-5753: kernels 4.19+ use a different nospec macro

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This commit is contained in:
Stéphane Lesimple 2019-11-23 18:01:36 +01:00
parent 36f98eff95
commit 4a3006e196
1 changed files with 30 additions and 1 deletions
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31
spectre-meltdown-checker.sh
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@ -1199,7 +1199,9 @@ check_kernel()
_mode="$2"
# checking the return code of readelf -h is not enough, we could get
# a damaged ELF file and validate it, check for stderr warnings too
_readelf_warnings=$("${opt_arch_prefix}readelf" -S "$_file" 2>&1 >/dev/null | tr "\n" "/"); ret=$?
# the warning "readelf: Warning: [16]: Link field (0) should index a symtab section./" can appear on valid kernels, ignore it
_readelf_warnings=$("${opt_arch_prefix}readelf" -S "$_file" 2>&1 >/dev/null | grep -v 'should index a symtab section' | tr "\n" "/"); ret=$?
_readelf_sections=$("${opt_arch_prefix}readelf" -S "$_file" 2>/dev/null | grep -c -e data -e text -e init)
_kernel_size=$(stat -c %s "$_file" 2>/dev/null || stat -f %z "$_file" 2>/dev/null || echo 10000)
_debug "check_kernel: ret=$? size=$_kernel_size sections=$_readelf_sections warnings=$_readelf_warnings"
@ -3232,6 +3234,33 @@ check_CVE_2017_5753_linux()
fi
fi
_info_nol "* Kernel has array_index_nospec (arm64): "
# in 4.19+ kernels, the mask_nospec64 asm64 macro is replaced by array_index_nospec, defined in nospec.h, and used in invoke_syscall()
# ffffff8008090a4c: 2a0203e2 mov w2, w2
# ffffff8008090a50: eb0200bf cmp x5, x2
# ffffff8008090a54: da1f03e2 ngc x2, xzr
# ffffff8008090a58: d503229f hint #0x14
# /!\ can also just be "csdb" instead of "hint #0x14" for native objdump
#
# if we have v1_mask_nospec or redhat_canonical_spectre>0, don't bother disassembling the kernel, the answer is no.
if [ -n "$v1_mask_nospec" ] || [ "$redhat_canonical_spectre" -gt 0 ]; then
pstatus yellow NO
elif [ -n "$kernel_err" ]; then
pstatus yellow UNKNOWN "couldn't check ($kernel_err)"
elif ! command -v perl >/dev/null 2>&1; then
pstatus yellow UNKNOWN "missing 'perl' binary, please install it"
elif ! command -v "${opt_arch_prefix}objdump" >/dev/null 2>&1; then
pstatus yellow UNKNOWN "missing '${opt_arch_prefix}objdump' tool, please install it, usually it's in the binutils package"
else
"${opt_arch_prefix}objdump" -d "$kernel" | perl -ne 'push @r, $_; /\s(hint|csdb)\s/ && $r[0]=~/\smov\s+(w\d+),\s+(w\d+)/ && $r[1]=~/\scmp\s+(x\d+),\s+(x\d+)/ && $r[2]=~/\sngc\s+$2,/ && exit(9); shift @r if @r>3'; ret=$?
if [ "$ret" -eq 9 ]; then
pstatus green YES "array_index_nospec macro is present and used"
v1_mask_nospec="arm64 array_index_nospec"
else
pstatus yellow NO
fi
fi
if [ "$opt_verbose" -ge 2 ] || { [ -z "$v1_mask_nospec" ] && [ "$redhat_canonical_spectre" != 1 ] && [ "$redhat_canonical_spectre" != 2 ]; }; then
# this is a slow heuristic and we don't need it if we already know the kernel is patched
# but still show it in verbose mode