Description:
------------
From https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=19581.

<?php
var_dump(exif_read_data('data://image/jpeg;base64,/9jhAAlFeGlmAAAg'));

Results in:

 	Uninitialized bytes in MemcmpInterceptorCommon at offset 1 inside [0x7010000006e8, 2)
	==1==WARNING: MemorySanitizer: use-of-uninitialized-value
	    #0 0x5004dc in __interceptor_bcmp /src/llvm-project/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc:885:10
	    #1 0x86693b in exif_process_TIFF_in_JPEG php-src/ext/exif/exif.c:3596:6
	    #2 0x861b7e in exif_scan_JPEG_header php-src/ext/exif/exif.c:3793:6
	    #3 0x8609eb in exif_scan_FILE_header php-src/ext/exif/exif.c:4186:8
	    #4 0x8602bb in exif_read_from_impl php-src/ext/exif/exif.c:4327:8
	    #5 0x858b52 in exif_read_from_stream php-src/ext/exif/exif.c:4344:8
	    #6 0x856001 in zif_exif_read_data php-src/ext/exif/exif.c:4434:9
	    #7 0x112596d in zend_call_function php-src/Zend/zend_execute_API.c:817:4
	    #8 0x11236e2 in _call_user_function_ex php-src/Zend/zend_execute_API.c:638:9
	    #9 0x1696c7a in fuzzer_call_php_func_zval php-src/sapi/fuzzer/fuzzer-sapi.c:247:2
	    #10 0x169596f in LLVMFuzzerTestOneInput php-src/sapi/fuzzer/fuzzer-exif.c:52:2
	    #11 0x481101 in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*, unsigned long) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:556:15
	    #12 0x46bc21 in fuzzer::RunOneTest(fuzzer::Fuzzer*, char const*, unsigned long) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerDriver.cpp:292:6
	    #13 0x4718de in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerDriver.cpp:774:9
	    #14 0x49b802 in main /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerMain.cpp:19:10
	    #15 0x7f3e6199882f in __libc_start_main /build/glibc-LK5gWL/glibc-2.23/csu/libc-start.c:291
	    #16 0x445098 in _start
	
	  Uninitialized value was created by a heap allocation
	    #0 0x4fc67d in malloc /src/llvm-project/compiler-rt/lib/msan/msan_interceptors.cpp:925:3
	    #1 0x1088155 in __zend_malloc php-src/Zend/zend_alloc.c:2975:14
	    #2 0x1082159 in _emalloc php-src/Zend/zend_alloc.c:2535:10
	    #3 0x865d76 in exif_file_sections_add php-src/ext/exif/exif.c:2042:10
	    #4 0x8618c0 in exif_scan_JPEG_header php-src/ext/exif/exif.c:3747:8
	    #5 0x8609eb in exif_scan_FILE_header php-src/ext/exif/exif.c:4186:8
	    #6 0x8602bb in exif_read_from_impl php-src/ext/exif/exif.c:4327:8
	    #7 0x858b52 in exif_read_from_stream php-src/ext/exif/exif.c:4344:8
	    #8 0x856001 in zif_exif_read_data php-src/ext/exif/exif.c:4434:9
	    #9 0x112596d in zend_call_function php-src/Zend/zend_execute_API.c:817:4
	    #10 0x11236e2 in _call_user_function_ex php-src/Zend/zend_execute_API.c:638:9
	    #11 0x1696c7a in fuzzer_call_php_func_zval php-src/sapi/fuzzer/fuzzer-sapi.c:247:2
	    #12 0x169596f in LLVMFuzzerTestOneInput php-src/sapi/fuzzer/fuzzer-exif.c:52:2
	    #13 0x481101 in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*, unsigned long) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:556:15
	    #14 0x46bc21 in fuzzer::RunOneTest(fuzzer::Fuzzer*, char const*, unsigned long) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerDriver.cpp:292:6
	    #15 0x4718de in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerDriver.cpp:774:9
	    #16 0x49b802 in main /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerMain.cpp:19:10
	    #17 0x7f3e6199882f in __libc_start_main /build/glibc-LK5gWL/glibc-2.23/csu/libc-start.c:291

I can't reproduce under valgrind, so also can't tell which versions are affected.