Re: [RFC PATCH] hw/net/e1000e: Do not abort() on invalid PSRCTL register value

[Jason Wang]

On 2020/5/29 下午3:17, Philippe Mathieu-Daudé wrote:
> Le ven. 29 mai 2020 08:36, Jason Wang <jasowang@redhat.com 
> <mailto:jasowang@redhat.com>> a écrit :
>
>
>     On 2020/5/25 下午8:23, Philippe Mathieu-Daudé wrote:
>     > libFuzzer found using 'qemu-system-i386 -M q35':
>     >
>     > qemu: hardware error: e1000e: PSRCTL.BSIZE0 cannot be zero
>     > CPU #0:
>     > EAX=00000000 EBX=00000000 ECX=00000000 EDX=00000663
>     > ESI=00000000 EDI=00000000 EBP=00000000 ESP=00000000
>     > EIP=0000fff0 EFL=00000002 [-------] CPL=0 II=0 A20=1 SMM=0 HLT=0
>     > ES =0000 00000000 0000ffff 00009300
>     > CS =f000 ffff0000 0000ffff 00009b00
>     > SS =0000 00000000 0000ffff 00009300
>     > DS =0000 00000000 0000ffff 00009300
>     > FS =0000 00000000 0000ffff 00009300
>     > GS =0000 00000000 0000ffff 00009300
>     > LDT=0000 00000000 0000ffff 00008200
>     > TR =0000 00000000 0000ffff 00008b00
>     > GDT=     00000000 0000ffff
>     > IDT=     00000000 0000ffff
>     > CR0=60000010 CR2=00000000 CR3=00000000 CR4=00000000
>     > DR0=00000000 DR1=00000000 DR2=00000000 DR3=00000000
>     > DR6=ffff0ff0 DR7=00000400
>     > EFER=0000000000000000
>     > FCW=037f FSW=0000 [ST=0] FTW=00 MXCSR=00001f80
>     > FPR0=0000000000000000 0000 FPR1=0000000000000000 0000
>     > FPR2=0000000000000000 0000 FPR3=0000000000000000 0000
>     > FPR4=0000000000000000 0000 FPR5=0000000000000000 0000
>     > FPR6=0000000000000000 0000 FPR7=0000000000000000 0000
>     > XMM00=00000000000000000000000000000000
>     XMM01=00000000000000000000000000000000
>     > XMM02=00000000000000000000000000000000
>     XMM03=00000000000000000000000000000000
>     > XMM04=00000000000000000000000000000000
>     XMM05=00000000000000000000000000000000
>     > XMM06=00000000000000000000000000000000
>     XMM07=00000000000000000000000000000000
>     > ==1988== ERROR: libFuzzer: deadly signal
>     >      #6 0x7fae4d3ea894 in __GI_abort (/lib64/libc.so.6+0x22894)
>     >      #7 0x563f4cc59a1d in hw_error (qemu-fuzz-i386+0xe8ca1d)
>     >      #8 0x563f4d7c93f2 in e1000e_set_psrctl
>     (qemu-fuzz-i386+0x19fc3f2)
>     >      #9 0x563f4d7b798f in e1000e_core_write
>     (qemu-fuzz-i386+0x19ea98f)
>     >      #10 0x563f4d7afc46 in e1000e_mmio_write
>     (qemu-fuzz-i386+0x19e2c46)
>     >      #11 0x563f4cc9a0a7 in memory_region_write_accessor
>     (qemu-fuzz-i386+0xecd0a7)
>     >      #12 0x563f4cc99c13 in access_with_adjusted_size
>     (qemu-fuzz-i386+0xeccc13)
>     >      #13 0x563f4cc987b4 in memory_region_dispatch_write
>     (qemu-fuzz-i386+0xecb7b4)
>     >
>     > It simply sent the following 2 I/O command to the e1000e
>     > PCI BAR #2 I/O region:
>     >
>     >    writew 0x0100 0x0c00 # RCTL =  E1000_RCTL_DTYP_MASK
>     >    writeb 0x2170 0x00   # PSRCTL = 0
>     >
>     > 2813 static void
>     > 2814 e1000e_set_psrctl(E1000ECore *core, int index, uint32_t val)
>     > 2815 {
>     > 2816     if (core->mac[RCTL] & E1000_RCTL_DTYP_MASK) {
>     > 2817
>     > 2818         if ((val & E1000_PSRCTL_BSIZE0_MASK) == 0) {
>     > 2819             hw_error("e1000e: PSRCTL.BSIZE0 cannot be zero");
>     > 2820         }
>     >
>     > Instead of calling hw_error() which abort the process (it is
>     > meant for CPU fatal error condition, not for device logging),
>     > log the invalid request with qemu_log_mask(LOG_GUEST_ERROR)
>     > and return ignoring the request.
>
>
> Maybe more understandable adding a comma after "return":
>
> "... and return, ignoring the request."


Fixed.


>     >
>     > Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org
>     <mailto:f4bug@amsat.org>>
>     > ---
>     > RFC because there might be something clever than returning...
>     > Probably worth a Cc:qemu-stable@ tag
>
>
>     I can't think of a better solution here. And the code looks safe
>     if we
>     accept zero value.
>
>     So I applied this patch.
>
>
> Thanks. Can you append the "Cc:qemu-stable@..." tag please?


Added.

Thanks


>     Thanks
>
>
>     > ---
>     >   hw/net/e1000e_core.c | 10 +++++++---
>     >   1 file changed, 7 insertions(+), 3 deletions(-)
>     >
>     > diff --git a/hw/net/e1000e_core.c b/hw/net/e1000e_core.c
>     > index d5676871fa..bcd186cac5 100644
>     > --- a/hw/net/e1000e_core.c
>     > +++ b/hw/net/e1000e_core.c
>     > @@ -34,9 +34,9 @@
>     >   */
>     >
>     >   #include "qemu/osdep.h"
>     > +#include "qemu/log.h"
>     >   #include "net/net.h"
>     >   #include "net/tap.h"
>     > -#include "hw/hw.h"
>     >   #include "hw/pci/msi.h"
>     >   #include "hw/pci/msix.h"
>     >   #include "sysemu/runstate.h"
>     > @@ -2816,11 +2816,15 @@ e1000e_set_psrctl(E1000ECore *core, int
>     index, uint32_t val)
>     >       if (core->mac[RCTL] & E1000_RCTL_DTYP_MASK) {
>     >
>     >           if ((val & E1000_PSRCTL_BSIZE0_MASK) == 0) {
>     > -            hw_error("e1000e: PSRCTL.BSIZE0 cannot be zero");
>     > +            qemu_log_mask(LOG_GUEST_ERROR,
>     > +                          "e1000e: PSRCTL.BSIZE0 cannot be zero");
>     > +            return;
>     >           }
>     >
>     >           if ((val & E1000_PSRCTL_BSIZE1_MASK) == 0) {
>     > -            hw_error("e1000e: PSRCTL.BSIZE1 cannot be zero");
>     > +            qemu_log_mask(LOG_GUEST_ERROR,
>     > +                          "e1000e: PSRCTL.BSIZE1 cannot be zero");
>     > +            return;
>     >           }
>     >       }
>     >