Messages in this thread Patch in this message | | | From | Chen Feng <> | Subject | [PATCH RFC] random: fix syzkaller fuzzer test int overflow | Date | Tue, 24 Oct 2017 15:44:17 +0800 |
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[pid:11940,cpu6,syz-executor][flp_ioctl]cmd[0x1] Restart is not permit ================================================================= UBSAN: Undefined behaviour in kernel/linux-4.4/drivers/char/random.c:676:19 signed integer overflow: 2147483645 + 268435455 cannot be represented in type 'int' CPU: 4 PID: 11941 Comm: syz-executor Not tainted 4.4.76+ #2 TGID: 11928 Comm: syz-executor Hardware name: hi3660 (DT) Call trace: [<ffffffa661090378>] dump_backtrace+0x0/0x314 [<ffffffa66109077c>] show_stack+0x1c/0x24 [<ffffffa66180cc54>] dump_stack+0xdc/0x130 [<ffffffa6618833d0>] ubsan_epilogue+0x18/0x6c [<ffffffa661883c5c>] handle_overflow+0x180/0x1d4 [<ffffffa661883cdc>] __ubsan_handle_add_overflow+0x2c/0x34 [<ffffffa661ab75a0>] credit_entropy_bits+0x358/0x9a8 [<ffffffa661ab85bc>] random_ioctl+0x338/0x384 [<ffffffa661399c74>] do_vfs_ioctl+0x60c/0xa4c [<ffffffa66139a150>] SyS_ioctl+0x9c/0xc0 [<ffffffa6610838b0>] el0_svc_naked+0x24/0x28 =================================================================
Signed-off-by: Chen Feng <puck.chen@hisilicon.com> Signed-off-by: Yukun Zhao <zhaoyukun@huawei.com> --- drivers/char/random.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/drivers/char/random.c b/drivers/char/random.c index 1ef2640..6f2bd6a 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -699,6 +699,11 @@ static void credit_entropy_bits(struct entropy_store *r, int nbits) if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig) goto retry; + if (INT_MAX - nbits < r->entropy_total) { + WARN_ON(1); + return; + } + r->entropy_total += nbits; if (!r->initialized && r->entropy_total > 128) { r->initialized = 1; -- 1.9.1
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