Re: [syzbot] [kernel?] KMSAN: kernel-infoleak-after-free in copy_siginfo_to_user (2)

Edward Adam Davis
2023-12-31T02:04:04Z

please test kernel-infoleak-after-free in copy_siginfo_to_user

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 861deac3b092

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index d8b5e13a2229..8bd346b10c6e 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -1033,7 +1033,7 @@ int ptrace_request(struct task_struct *child, long request,
{
bool seized = child->ptrace & PT_SEIZED;
int ret = -EIO;
- kernel_siginfo_t siginfo, *si;
+ kernel_siginfo_t siginfo, *si, *psiginfo;
void __user *datavp = (void __user *) data;
unsigned long __user *datalp = datavp;
unsigned long flags;
@@ -1061,9 +1061,13 @@ int ptrace_request(struct task_struct *child, long request,
break;

case PTRACE_GETSIGINFO:
- ret = ptrace_getsiginfo(child, &siginfo);
+ psiginfo = kvmalloc(sizeof(kernel_siginfo_t), GFP_KERNEL);
+ if (!psiginfo)
+ break;
+ ret = ptrace_getsiginfo(child, psiginfo);
if (!ret)
- ret = copy_siginfo_to_user(datavp, &siginfo);
+ ret = copy_siginfo_to_user(datavp, psiginfo);
+ kvfree(psiginfo);
break;