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).
Signed-off-by: Mark Wielaard <m...@klomp.org>
---
libdwfl/ChangeLog | 6 ++++++
libdwfl/dwfl_segment_report_module.c | 12 ++++++++++++
2 files changed, 18 insertions(+)
diff --git a/libdwfl/ChangeLog b/libdwfl/ChangeLog
index 6c7e0c4a..ac0fbe0f 100644
--- a/libdwfl/ChangeLog
+++ b/libdwfl/ChangeLog
@@ -1,3 +1,9 @@
+2021-12-19 Mark Wielaard <m...@klomp.org>
+
+ * dwfl_segment_report_module.c (dwfl_segment_report_module): Copy
+ ph_buffer and set xlatefrom.d_buf to phdrsp when ph_buffer is not
+ aligned.
+
2021-12-19 Mark Wielaard <m...@klomp.org>
* dwfl_segment_report_module.c (dwfl_segment_report_module): Copy
diff --git a/libdwfl/dwfl_segment_report_module.c
b/libdwfl/dwfl_segment_report_module.c
index 7f756392..de190e90 100644
--- a/libdwfl/dwfl_segment_report_module.c
+++ b/libdwfl/dwfl_segment_report_module.c
@@ -461,6 +461,18 @@ dwfl_segment_report_module (Dwfl *dwfl, int ndx, const
char *name,
xlateto.d_buf = phdrsp;
xlateto.d_size = phdrsp_bytes;
+ /* ph_ buffer 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). */
+ size_t phdr_align = (class32
+ ? __alignof__ (Elf32_Phdr)
+ : __alignof__ (Elf64_Phdr));
+ if (((uintptr_t) ph_buffer & (phdr_align - 1)) != 0)
+ {
+ memcpy (phdrsp, ph_buffer, phdrsp_bytes);
+ xlatefrom.d_buf = phdrsp;
+ }
+
/* Track the bounds of the file visible in memory. */
GElf_Off file_trimmed_end = 0; /* Proper p_vaddr + p_filesz end. */
GElf_Off file_end = 0; /* Rounded up to effective page size. */
--
2.30.2
