https://sourceware.org/bugzilla/show_bug.cgi?id=28720
Bug ID: 28720
Summary: UBSan: member access within misaligned address
0x7f6e8d80f142 for type 'struct Elf32_Phdr', which
requires 4 byte alignment
Product: elfutils
Version: unspecified
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: libdw
Assignee: unassigned at sourceware dot org
Reporter: evvers at ya dot ru
CC: elfutils-devel at sourceware dot org
Target Milestone: ---
Created attachment 13872
--> https://sourceware.org/bugzilla/attachment.cgi?id=13872&action=edit
File triggering misaligned access
While I was testing
https://sourceware.org/pipermail/elfutils-devel/2021q4/004584.html I passed
FUZZ_TIME=3600 to the test to run it for an hour and in the process it ran into
another misaligned access. Just to make sure it isn't
https://sourceware.org/bugzilla/show_bug.cgi?id=28685 I pulled the master
branch with the "fuzz" branch included. It can be reproduced with
`./src/stack`:
```
autoreconf -i -f
./configure --enable-maintainer-mode --enable-sanitize-undefined
make -j$(nproc) V=1
UBSAN_OPTIONS=print_stacktrace=1:print_summary=1
LD_LIBRARY_PATH="./libdw;./libelf" ./src/stack --core
../SIGABRT.PC.7fffe516d84c.STACK.d7ffe76d7.CODE.-6.ADDR.0.INSTR.mov____%eax,%ebp.fuzz
gelf_xlate.h:42:1: runtime error: member access within misaligned address
0x7f3827783142 for type 'struct Elf32_Phdr', which requires 4 byte alignment
0x7f3827783142: note: pointer points here
00 00 00 10 00 00 00 00 00 c5 00 10 00 00 00 00 00 00 00 10 00 00 00 00 00
00 01 00 00 00 06 15
^
#0 0x7f38295f992c in Elf32_cvt_Phdr
/home/vagrant/elfutils/libelf/gelf_xlate.h:42
#1 0x7f38295f8363 in elf32_xlatetom
/home/vagrant/elfutils/libelf/elf32_xlatetom.c:104
#2 0x7f382952a821 in dwfl_link_map_report
/home/vagrant/elfutils/libdwfl/link_map.c:925
#3 0x7f382952de80 in _new.dwfl_core_file_report
/home/vagrant/elfutils/libdwfl/core-file.c:548
#4 0x402fa0 in parse_opt /home/vagrant/elfutils/src/stack.c:595
#5 0x7f382878b471 in argp_parse (/lib64/libc.so.6+0x11e471)
#6 0x4026aa in main /home/vagrant/elfutils/src/stack.c:695
#7 0x7f382869a55f in __libc_start_call_main (/lib64/libc.so.6+0x2d55f)
#8 0x7f382869a60b in __libc_start_main_impl (/lib64/libc.so.6+0x2d60b)
#9 0x402944 in _start (/home/vagrant/elfutils/src/stack+0x402944)
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior gelf_xlate.h:42:1 in
```
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