zdump/dfi: Fix illegal memory access in dfi_cpu_add_from_lc()

Check that a CPU's lowcore address falls within a valid memory region
before accessing it. This prevents potential illegal memory accesses
in case a dump contains invalid CPU lowcore addresses.

This bug was found with AFL fuzzing and ASAN.

Starting program: /root/s390-tools/zdump/zgetdump -iVVVVV /root/zgetdump-fuzzing/findings/crashes/id:000004,sig:06,src:000005,op:flip32,pos:3055
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".
TRACE: DFI initialization
DEBUG: DFI trying s390tape
DEBUG: DFI s390tape returned with rc -19
DEBUG: DFI trying devmem
DEBUG: DFI devmem returned with rc -19
DEBUG: DFI trying s390mv_ext
DEBUG: DFI s390mv_ext returned with rc -19
DEBUG: DFI trying s390mv
DEBUG: DFI s390mv returned with rc -19
DEBUG: DFI trying s390_ext
DEBUG: DFI S390 extended initialization
DEBUG: DFI s390_ext returned with rc -19
DEBUG: DFI trying s390
DEBUG: DFI S390 initialization
 INFO: DFI S390 version 5
DEBUG: DFI S390 mem_size 0x00000000000dbba0
DEBUG: DFI add vol mem chunk start 0x0000000000000000 size 0x00000000000dbba0 volnr 0

[snip]

TRACE: DFI virt mem read addr 0x0000000000000000 size 0x0000000000002000
TRACE: DFI virt mem read addr 0x0000000000000000 size 0x0000000000002000
TRACE: DFI virt mem read addr 0x0000000000000000 size 0x0000000000002000
TRACE: DFI virt mem read addr 0x0000000000000000 size 0x0000000000002000
TRACE: DFI virt mem read addr 0x0000000000000000 size 0x0000000000002000
TRACE: DFI virt mem read addr 0x0000000000000000 size 0x0000000000002000
TRACE: DFI virt mem read addr 0x0000000000000000 size 0x0000000000002000
TRACE: DFI virt mem read addr 0x0000000000000000 size 0x0000000000002000
TRACE: DFI virt mem read addr 0x0000000000000000 size 0x0000000000002000
TRACE: DFI virt mem read addr 0x0000000000000000 size 0x0000000000002000
TRACE: DFI virt mem read addr 0x0000000000000000 size 0x0000000000002000
TRACE: DFI virt mem read addr 0x0000000000000000 size 0x0000000000002000
TRACE: DFI virt mem read addr 0x0000000000000000 size 0x0000000000002000
TRACE: DFI virt mem read addr 0x0000000000000000 size 0x0000000000002000
TRACE: DFI virt mem read addr 0x00000000000000ff size 0x0000000000002000
TRACE: DFI virt mem read addr 0x00000000ffffff00 size 0x0000000000002000

Program received signal SIGSEGV, Segmentation fault.
0x000000000100fbb0 in mem_read (cnt=<optimized out>, buf=0x3ffffffc7d0, addr=4294967040, mem=0x104b218 <l+152>) at dfi.c:339
339                     size = MIN(cnt - copied, mem_chunk->end - addr + 1);
Missing separate debuginfos, use: dnf debuginfo-install fuse-libs-2.9.9-11.fc34.s390x glibc-2.33-20.1.ibm.fc34.s390x libasan-11.0.1-0.3.1.ibm.fc34.s390x libgcc-11.0.1-0.3.1.ibm.fc34.s390x libstdc++-11.0.1-0.3.1.ibm.fc34.s390x zlib-1.2.11-26.fc34.s390x
(gdb) bt

Signed-off-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
This commit is contained in:
Alexander Egorenkov
2021-09-03 20:32:05 +02:00
committed by Jan Höppner
parent 094057e265
commit f15e32cdb1
8 changed files with 40 additions and 16 deletions
+1 -1
View File
@@ -142,7 +142,7 @@ extern struct dfi_cpu *dfi_cpu(unsigned int cpu_nr);
extern void dfi_cpu_add(struct dfi_cpu *cpu);
extern unsigned int dfi_cpu_cnt(void);
extern enum dfi_cpu_content dfi_cpu_content(void);
extern void dfi_cpu_add_from_lc(u32 lc_addr);
extern int dfi_cpu_add_from_lc(u32 lc_addr);
#define DFI_VX_SA_SIZE (32 * 16)
extern int dfi_cpu_lc_has_vx_sa(void *lc);