| Message ID | 20230926114343.1061739-2-twuufnxlz@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | riscv: fix out of bounds in walk_stackframe | expand |
On Tue, Sep 26, 2023 at 07:43:44PM +0800, Edward AD wrote: > Increase the check on the frame after assigning its value. This is to prevent > frame access from crossing boundaries. > > Closes: https://lore.kernel.org/all/20230926105949.1025995-2-twuufnxlz@gmail.com/ > Fixes: 5d8544e2d007 ("RISC-V: Generic library routines and assembly") > Reported-and-tested-by: syzbot+8d2757d62d403b2d9275@syzkaller.appspotmail.com > Link: https://lore.kernel.org/all/0000000000000170df0605ccf91a@google.com/T/ > Signed-off-by: Edward AD <twuufnxlz@gmail.com> > --- > arch/riscv/kernel/stacktrace.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c > index 64a9c093aef9..53bd18672329 100644 > --- a/arch/riscv/kernel/stacktrace.c > +++ b/arch/riscv/kernel/stacktrace.c > @@ -54,6 +54,8 @@ void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs, > break; > /* Unwind stack frame */ > frame = (struct stackframe *)fp - 1; > + if (!virt_addr_valid(frame)) > + break; > sp = fp; > if (regs && (regs->epc == pc) && (frame->fp & 0x7)) { > fp = frame->ra; > -- > 2.25.1 > Hi, This is the friendly patch-bot of Greg Kroah-Hartman. You have sent him a patch that has triggered this response. He used to manually respond to these common problems, but in order to save his sanity (he kept writing the same thing over and over, yet to different people), I was created. Hopefully you will not take offence and will fix the problem in your patch and resubmit it so that it can be accepted into the Linux kernel tree. You are receiving this message because of the following common error(s) as indicated below: - You have marked a patch with a "Fixes:" tag for a commit that is in an older released kernel, yet you do not have a cc: stable line in the signed-off-by area at all, which means that the patch will not be applied to any older kernel releases. To properly fix this, please follow the documented rules in the Documetnation/process/stable-kernel-rules.rst file for how to resolve this. If you wish to discuss this problem further, or you have questions about how to resolve this issue, please feel free to respond to this email and Greg will reply once he has dug out from the pending patches received from other developers. thanks, greg k-h's patch email bot
Hi Edward, On 26/09/2023 13:43, Edward AD wrote: > Increase the check on the frame after assigning its value. This is to prevent > frame access from crossing boundaries. > > Closes: https://lore.kernel.org/all/20230926105949.1025995-2-twuufnxlz@gmail.com/ > Fixes: 5d8544e2d007 ("RISC-V: Generic library routines and assembly") > Reported-and-tested-by: syzbot+8d2757d62d403b2d9275@syzkaller.appspotmail.com > Link: https://lore.kernel.org/all/0000000000000170df0605ccf91a@google.com/T/ > Signed-off-by: Edward AD <twuufnxlz@gmail.com> > --- > arch/riscv/kernel/stacktrace.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c > index 64a9c093aef9..53bd18672329 100644 > --- a/arch/riscv/kernel/stacktrace.c > +++ b/arch/riscv/kernel/stacktrace.c > @@ -54,6 +54,8 @@ void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs, > break; > /* Unwind stack frame */ > frame = (struct stackframe *)fp - 1; > + if (!virt_addr_valid(frame)) > + break; > sp = fp; > if (regs && (regs->epc == pc) && (frame->fp & 0x7)) { > fp = frame->ra; virt_addr_valid() works on kernel linear addresses, not on vmalloc addresses, which is the case here (0xff20000006d37c38 belongs to the vmalloc region: see https://elixir.bootlin.com/linux/latest/source/Documentation/riscv/vm-layout.rst#L125). So this fix can't work. I'm a bit surprised though of this out-of-bounds access since CONFIG_FRAME_POINTER is enabled, so there may be a real issue here (the console output is horrible, lots of backtraces, which is weird), so it may be worth digging into that. Thanks, Alex
Oh and BTW, any idea why linux-riscv was not in CC for the initial report? On 28/09/2023 10:02, Alexandre Ghiti wrote: > Hi Edward, > > On 26/09/2023 13:43, Edward AD wrote: >> Increase the check on the frame after assigning its value. This is to >> prevent >> frame access from crossing boundaries. >> >> Closes: >> https://lore.kernel.org/all/20230926105949.1025995-2-twuufnxlz@gmail.com/ >> Fixes: 5d8544e2d007 ("RISC-V: Generic library routines and assembly") >> Reported-and-tested-by: >> syzbot+8d2757d62d403b2d9275@syzkaller.appspotmail.com >> Link: >> https://lore.kernel.org/all/0000000000000170df0605ccf91a@google.com/T/ >> Signed-off-by: Edward AD <twuufnxlz@gmail.com> >> --- >> arch/riscv/kernel/stacktrace.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/arch/riscv/kernel/stacktrace.c >> b/arch/riscv/kernel/stacktrace.c >> index 64a9c093aef9..53bd18672329 100644 >> --- a/arch/riscv/kernel/stacktrace.c >> +++ b/arch/riscv/kernel/stacktrace.c >> @@ -54,6 +54,8 @@ void notrace walk_stackframe(struct task_struct >> *task, struct pt_regs *regs, >> break; >> /* Unwind stack frame */ >> frame = (struct stackframe *)fp - 1; >> + if (!virt_addr_valid(frame)) >> + break; >> sp = fp; >> if (regs && (regs->epc == pc) && (frame->fp & 0x7)) { >> fp = frame->ra; > > > virt_addr_valid() works on kernel linear addresses, not on vmalloc > addresses, which is the case here (0xff20000006d37c38 belongs to the > vmalloc region: see > https://elixir.bootlin.com/linux/latest/source/Documentation/riscv/vm-layout.rst#L125). > So this fix can't work. > > I'm a bit surprised though of this out-of-bounds access since > CONFIG_FRAME_POINTER is enabled, so there may be a real issue here > (the console output is horrible, lots of backtraces, which is weird), > so it may be worth digging into that. > > Thanks, > > Alex > > > > _______________________________________________ > linux-riscv mailing list > linux-riscv@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-riscv
diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c index 64a9c093aef9..53bd18672329 100644 --- a/arch/riscv/kernel/stacktrace.c +++ b/arch/riscv/kernel/stacktrace.c @@ -54,6 +54,8 @@ void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs, break; /* Unwind stack frame */ frame = (struct stackframe *)fp - 1; + if (!virt_addr_valid(frame)) + break; sp = fp; if (regs && (regs->epc == pc) && (frame->fp & 0x7)) { fp = frame->ra;
Increase the check on the frame after assigning its value. This is to prevent frame access from crossing boundaries. Closes: https://lore.kernel.org/all/20230926105949.1025995-2-twuufnxlz@gmail.com/ Fixes: 5d8544e2d007 ("RISC-V: Generic library routines and assembly") Reported-and-tested-by: syzbot+8d2757d62d403b2d9275@syzkaller.appspotmail.com Link: https://lore.kernel.org/all/0000000000000170df0605ccf91a@google.com/T/ Signed-off-by: Edward AD <twuufnxlz@gmail.com> --- arch/riscv/kernel/stacktrace.c | 2 ++ 1 file changed, 2 insertions(+)