The xlate functions only handle correctly aligned buffers. But they do handle src == dest. So if the source buffer isn't aligned correctly just copy it first into the destination (which is already correctly aligned).
https://sourceware.org/bugzilla/show_bug.cgi?id=28720 Signed-off-by: Mark Wielaard <m...@klomp.org> --- libdwfl/ChangeLog | 5 +++++ libdwfl/dwfl_segment_report_module.c | 12 ++++++++++++ 2 files changed, 17 insertions(+) diff --git a/libdwfl/ChangeLog b/libdwfl/ChangeLog index f8319f44..aace969f 100644 --- a/libdwfl/ChangeLog +++ b/libdwfl/ChangeLog @@ -1,3 +1,8 @@ +2022-01-03 Mark Wielaard <m...@klomp.org> + + * dwfl_segment_report_module.c (dwfl_segment_report_module): Copy + dyn_data and set xlatefrom.d_buf to dyns when dyns is not aligned. + 2022-01-03 Mark Wielaard <m...@klomp.org> * link_map.c (read_addrs): Fix buffer_available nb overflow. diff --git a/libdwfl/dwfl_segment_report_module.c b/libdwfl/dwfl_segment_report_module.c index 5bef249e..1461ae26 100644 --- a/libdwfl/dwfl_segment_report_module.c +++ b/libdwfl/dwfl_segment_report_module.c @@ -844,7 +844,19 @@ dwfl_segment_report_module (Dwfl *dwfl, int ndx, const char *name, xlateto.d_buf = dyns; xlateto.d_size = dyn_filesz; + /* dyn_data may be unaligned, in which case xlatetom would not work. + xlatetom does work when the in and out d_buf are equal (but not + for any other overlap). */ bool is32 = (ei_class == ELFCLASS32); + size_t dyn_align = (is32 + ? __alignof__ (Elf32_Dyn) + : __alignof__ (Elf64_Dyn)); + if (((uintptr_t) dyn_data & (dyn_align - 1)) != 0) + { + memcpy (dyns, dyn_data, dyn_filesz); + xlatefrom.d_buf = dyns; + } + if ((is32 && elf32_xlatetom (&xlateto, &xlatefrom, ei_data) != NULL) || (!is32 && elf64_xlatetom (&xlateto, &xlatefrom, ei_data) != NULL)) { -- 2.30.2