Null pointer dereference in libr/bin/format/mach0/mach0.c in radareorg/radare2 in radareorg/radare2


Reported on

May 9th 2022

This vulnerability is of type heap-buffer-overflow. And after quick investigation I think it is very likely to be successfully exploited to remote code execution. The bug exists in latest stable release (radare2-5.6.8) and lastest master branch (5a9e0a19ba07e35382776fed9da2649ac824f526, updated in May 09, 2022). Specifically, the vulnerable code (located at libr/bin/format/mach0/mach0.c) and the bug's basic explanation are highlighted as follows:

4578                            ut64 page_end_idx = (R_MIN (limit_end, end) - start) / page_size;
4579                            for (; page_idx <= page_end_idx; page_idx++) {
4580                                    if (page_idx >= bin->chained_starts[i]->page_count) {
4581                                            break;
4582                                    }
// Null pointer dereference here.
4583                                    ut16 page_start = bin->chained_starts[i]->page_start[page_idx];
4584                                    if (page_start == DYLD_CHAINED_PTR_START_NONE) {
4585                                            continue;
4586                                    }
4587                                    ut64 cursor = start + page_idx * page_size + page_start;

Build the radare2 (5a9e0a19ba07e35382776fed9da2649ac824f526, updated in May 09, 2022) and run it using the input POC.

# build the radare2 with address sanitizer
export CFLAGS=" -fsanitize=address "; export CXXFLAGS=" -fsanitize=address "; export LDFLAGS=" -fsanitize=address ";
CFGARG=" --enable-shared=no " PREFIX=`realpath install` bash sys/
# disable some features of address sanitizer to avoid false positives
export ASAN_OPTIONS=detect_leaks=0:abort_on_error=1:symbolize=0:allocator_may_return_null=1:detect_odr_violation=0
# trigger the crash
./radare2 -A -q POC_FILE

The crash stack is:

==17553==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000 (pc 0x7f22529f7d6e bp 0x7ffdf8924410 sp 0x7ffdf8923f40 T0)
==17553==The signal is caused by a READ memory access.
==17553==Hint: address points to the zero page.
    #0 0x7f22529f7d6e  (/src/cmdline-fuzz/exprs/radare2-5.5.4/src/install/lib/
    #1 0x7f22529b481e  (/src/cmdline-fuzz/exprs/radare2-5.5.4/src/install/lib/
    #2 0x7f225653869b  (/src/cmdline-fuzz/exprs/radare2-5.5.4/src/install/lib/
    #3 0x7f2256d42087  (/src/cmdline-fuzz/exprs/radare2-5.5.4/src/install/lib/
    #4 0x7f2256d2b614  (/src/cmdline-fuzz/exprs/radare2-5.5.4/src/install/lib/
    #5 0x7f22529ef49f  (/src/cmdline-fuzz/exprs/radare2-5.5.4/src/install/lib/
    #6 0x7f22529f481b  (/src/cmdline-fuzz/exprs/radare2-5.5.4/src/install/lib/
    #7 0x7f22526f66d9  (/src/cmdline-fuzz/exprs/radare2-5.5.4/src/install/lib/
    #8 0x7f22526f4cd2  (/src/cmdline-fuzz/exprs/radare2-5.5.4/src/install/lib/
    #9 0x7f22526d9b65  (/src/cmdline-fuzz/exprs/radare2-5.5.4/src/install/lib/
    #10 0x7f225267db72  (/src/cmdline-fuzz/exprs/radare2-5.5.4/src/install/lib/
    #11 0x7f225267cb54  (/src/cmdline-fuzz/exprs/radare2-5.5.4/src/install/lib/
    #12 0x7f2253910893  (/src/cmdline-fuzz/exprs/radare2-5.5.4/src/install/lib/
    #13 0x7f2256acc154  (/src/cmdline-fuzz/exprs/radare2-5.5.4/src/install/lib/
    #14 0x7f225683a0b2  (/lib/x86_64-linux-gnu/
    #15 0x5634bce5339d  (/src/cmdline-fuzz/exprs/radare2-5.5.4/radare2+0x1e39d)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV (/src/cmdline-fuzz/exprs/radare2-5.5.4/src/install/lib/


It is likely to be exploitable. For more general description of heap buffer overflow, see CWE.


We are processing your report and will contact the radareorg/radare2 team within 24 hours. 19 days ago
We have contacted a member of the radareorg/radare2 team and are waiting to hear back 18 days ago
pancake validated this vulnerability 18 days ago
Han0nly has been awarded the disclosure bounty
The fix bounty is now up for grabs
The researcher's credibility has increased: +7
pancake confirmed that a fix has been merged on a5aafb 18 days ago
pancake has been awarded the fix bounty
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