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List:       linaro-kernel
Subject:    [PATCH v2 04/10] syzkaller-start: Add [--gdb] option to start qemu for kernel gdb debug
From:       Tudor Ambarus <tudor.ambarus () linaro ! org>
Date:       2022-12-23 13:46:22
Message-ID: 20221223134628.2861596-5-tudor.ambarus () linaro ! org
[Download RAW message or body]

Add config option to start qemu for kernel gdb debug.

Specify the nokaslr kernel parameter to disable kernel randomization,
that is, cause the kernel to be loaded at its standard location.

Set norandmaps so that we do not use address space randomization.

Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
---
 syzkaller-start | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/syzkaller-start b/syzkaller-start
index 55b8a04..305d09d 100644
--- a/syzkaller-start
+++ b/syzkaller-start
@@ -10,10 +10,12 @@ occurence=1
 
 function usage()
 {
-    echo "Usage: $(basename $0) [<URL or ID> <report occurence>] [--again]"
+    echo "Usage: $(basename $0) [<URL or ID> <report occurence>] [--again] [--gdb]"
     echo
     echo -e "\t--again"
     echo -e "\t\tUse the current kernel commit and run qemu directly."
+    echo -e "\t--gdb"
+    echo -e "\t\tdebug with gdb"
     exit 1
 }
 
@@ -37,6 +39,9 @@ while [ $# -gt 0 ]; do
 	--again|-a)
 	    AGAIN=true
 	    ;;
+	--gdb)
+	    GDB="-s -S"
+	    ;;
 	--norepro|-n)
 	    NOREPRO=true
 	    ;;
@@ -60,6 +65,10 @@ if [ "${url}" == "" ]; then
     usage
 fi
 
+if [ -n "${GDB}" ]; then
+    KERNEL_PARAMS="nokaslr norandmaps"
+fi
+
 reset # Required on subsequent runs, since QEMU borks the terminal
 
 print_blue "Starting SyzKaller Repro"
@@ -292,6 +301,10 @@ oldconfig="ccache make KBUILD_OUTPUT=${BUILDDIR} CC=${COMPILER} oldconfig"
 echo "${oldconfig}"
 yes "" | ${oldconfig}
 
+if [ -n "${GDB}" ]; then
+    scripts/config --file ${BUILDDIR}/.config --enable GDB_SCRIPTS
+fi
+
 if grep -q KASAN_STACK_ENABLE lib/Kconfig.kasan; then
     scripts/config --file ${BUILDDIR}/.config --enable  KASAN_STACK_ENABLE
     scripts/config --file ${BUILDDIR}/.config --set-val KASAN_STACK         1
@@ -314,7 +327,7 @@ if [[ -z "${AGAIN}" && -z "${NOREPRO}" ]]; then
     read
 fi
 
-qemu-system-x86_64 -smp 8 -m 16G -enable-kvm -cpu host -no-reboot               \
+qemu-system-x86_64 -smp 8 -m 16G -enable-kvm -cpu host -no-reboot ${GDB}        \
     -kernel ${BUILDDIR}/arch/x86/boot/bzImage -nographic                        \
     -net user,host=10.0.2.10,hostfwd=tcp::10022-:22                             \
     -net nic,model=virtio-net-pci                                               \
@@ -323,4 +336,4 @@ qemu-system-x86_64 -smp 8 -m 16G -enable-kvm -cpu host -no-reboot
     -drive file=${IMAGEDIR}/${IMAGE},format=raw,if=none,id=d0                   \
     -chardev stdio,id=char0,mux=on,logfile=serial.out,signal=off                \
     -serial chardev:char0 -mon chardev=char0                                    \
-    -append "root=/dev/sda1 rw console=ttyAMA0 panic_on_warn=0"
+    -append "root=/dev/sda1 ${KERNEL_PARAMS} rw console=ttyAMA0 panic_on_warn=0"
-- 
2.34.1

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