syzbot-repro.ktest: Run syzbot reproducers in a single command

Example usage, to reproduce locally the bug https://syzkaller.appspot.com/bug?extid=f074d2e31d8d35a6a38c
  build-test-kernel run -I ~/ktest/tests/syzbot-repro.ktest f074d2e31d8d35a6a38c
or, with an optionl crash index:
  build-test-kernel run -I ~/ktest/tests/syzbot-repro.ktest f074d2e31d8d35a6a38c 3

The syzbot-get tool needs to first be built and installed, run
  cargo install --path "path to ktest"

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

5 files changed, 137 insertions, 2 deletions

diff --git a/build-test-kernel b/build-test-kernel
index 61b88cd..72fbacb 100755
--- a/build-test-kernel
+++ b/build-test-kernel
@@ -198,7 +198,11 @@ build_kernel()
 	mv "$kconfig" "$kconfig".bak
     fi
 
-    new_config
+    if [[ -z $ktest_kconfig_base ]]; then
+	new_config
+    else
+	cp "$ktest_kconfig_base" "$kconfig"
+    fi
 
     log_verbose "kernel_config_require: ${ktest_kernel_config_require[@]}  ${ktest_kernel_config_require_soft[@]}"
 
diff --git a/lib/parse-test.sh b/lib/parse-test.sh
index 42a476e..291211a 100644
--- a/lib/parse-test.sh
+++ b/lib/parse-test.sh
@@ -2,7 +2,9 @@
 parse_test_deps()
 {
     export ktest_crashdump
-    eval $("$ktest_test" deps)
+    export ktest_out
+
+    eval $( "$ktest_test" deps $ktest_testargs )
 
     parse_arch "$ktest_arch"
 
diff --git a/src/bin/syzbot-get.rs b/src/bin/syzbot-get.rs
new file mode 100644
index 0000000..9ecafa0
--- /dev/null
+++ b/src/bin/syzbot-get.rs
@@ -0,0 +1,92 @@
+use std::path::PathBuf;
+use clap::Parser;
+use serde_derive::Deserialize;
+
+#[derive(Parser)]
+#[command(author, version, about, long_about = None)]
+struct Args {
+    #[arg(short, long)]
+    id:         String,
+    #[arg(short, long)]
+    idx:        Option<usize>,
+    #[arg(short, long)]
+    output:     PathBuf,
+    #[arg(short, long)]
+    verbose:    bool,
+}
+
+#[allow(dead_code)]
+#[derive(Deserialize, Debug)]
+struct SyzCrash {
+    title:                  String,
+    #[serde(rename = "syz-reproducer")]
+    syz_reproducer:         Option<String>,
+    #[serde(rename = "c-reproducer")]
+    c_reproducer:           Option<String>,
+    #[serde(rename = "kernel-config")]
+    kernel_config:          String,
+    #[serde(rename = "kernel-source-git")]
+    kernel_source_git:      String,
+    #[serde(rename = "kernel-source-commit")]
+    kernel_source_commit:   String,
+    #[serde(rename = "syzkaller-git")]
+    syzkaller_git:          String,
+    #[serde(rename = "syzkaller-commit")]
+    syzkaller_commit:       String,
+    #[serde(rename = "crash-report-link")]
+    crash_report_link:      String,
+}
+
+#[allow(dead_code)]
+#[derive(Deserialize, Debug)]
+struct SyzBug {
+    version:        usize,
+    title:          String,
+    id:             String,
+    #[serde(default)]
+    discussions:    Vec<String>,
+    crashes:        Vec<SyzCrash>,
+}
+
+fn get_syz_url(url: &String) -> String {
+    let url = format!("https://syzkaller.appspot.com{}", url);
+    reqwest::blocking::get(url).unwrap().text().unwrap()
+}
+
+fn fetch_syz_url(args: &Args, url: &String, fname: &String) {
+    let fname = args.output.join(fname);
+    if !fname.exists() {
+        if args.verbose { eprintln!("fetching {} => {:?}", &url, &fname); }
+
+        std::fs::write(fname, get_syz_url(url)).ok();
+    } else {
+        if args.verbose { eprintln!("have {} => {:?}", &url, &fname); }
+    }
+}
+
+fn fetch_syz_crash(args: &Args, crash: &SyzCrash, idx: usize) {
+    fetch_syz_url(&args, &crash.kernel_config, &format!("{}.{}.kconfig", args.id, idx));
+
+    if let Some(r) = &crash.c_reproducer.as_ref() {
+        fetch_syz_url(&args, r, &format!("{}.{}.repro.c", args.id, idx));
+    }
+}
+
+fn main() {
+    let args = Args::parse();
+
+    let bug_json = get_syz_url(&format!("/bug?json=1&extid={}", args.id));
+    let bug: SyzBug = serde_json::from_str(&bug_json).unwrap();
+
+    if args.verbose { eprintln!("{:?}", &bug); }
+
+    std::fs::create_dir_all(&args.output).ok();
+
+    if let Some(idx) = args.idx {
+        fetch_syz_crash(&args, &bug.crashes[idx], idx);
+    } else {
+        for (idx, crash) in bug.crashes.iter().enumerate() {
+            fetch_syz_crash(&args, &crash, idx);
+        }
+    }
+}
diff --git a/tests/prelude.sh b/tests/prelude.sh
index b1bc878..93ede2b 100644
--- a/tests/prelude.sh
+++ b/tests/prelude.sh
@@ -35,7 +35,9 @@ if [[ ! -v ktest_cpus ]]; then
     ktest_qemu_append=()
     ktest_compiler=gcc
     ktest_allow_taint=false
+
     ktest_tests_unknown=false
+    ktest_kconfig_base=
 
     BUILD_ON_HOST=""
 fi
@@ -355,6 +357,7 @@ main()
 	    echo "ktest_qemu_append=(${ktest_qemu_append[@]})"
 	    echo "ktest_allow_taint=$ktest_allow_taint"
 	    echo "ktest_tests_unknown=$ktest_tests_unknown"
+	    echo "ktest_kconfig_base=$ktest_kconfig_base"
 	    ;;
 	init)
 	    create_ktest_user
diff --git a/tests/syzbot-repro.ktest b/tests/syzbot-repro.ktest
new file mode 100755
index 0000000..fa9b131
--- /dev/null
+++ b/tests/syzbot-repro.ktest
@@ -0,0 +1,34 @@
+#!/usr/bin/env bash
+#
+# Run syzbot reproducers:
+#
+# Example usage, to reproduce locally the bug https://syzkaller.appspot.com/bug?extid=f074d2e31d8d35a6a38c
+#   build-test-kernel run -I ~/ktest/tests/syzbot-repro.ktest f074d2e31d8d35a6a38c
+# or, with an optionl crash index:
+#   build-test-kernel run -I ~/ktest/tests/syzbot-repro.ktest f074d2e31d8d35a6a38c 3
+#
+# The syzbot-get tool first needs to be built and installed, run
+#   cargo install --path "path to ktest"
+
+. $(dirname $(readlink -e "${BASH_SOURCE[0]}"))/test-libs.sh
+
+ktest_tests_unknown=true
+
+if [[ $1 == "deps" ]]; then
+    syz_id=$2
+    crash_idx=${3:-"0"}
+
+    syzbot-get --output "$ktest_out/syzbot" --id $syz_id --idx $crash_idx
+    ktest_kconfig_base="$ktest_out/syzbot/$syz_id.$crash_idx.kconfig"
+fi
+
+run_test()
+{
+    syz_id=$1
+    crash_idx=${2:-"0"}
+
+    gcc -O2 -Wall -o /tmp/syz-repro "$ktest_out/syzbot/$syz_id.$crash_idx.repro.c"
+    /tmp/syz-repro
+}
+
+main "$@"