* [PATCH] libdwfl: Handle unaligned Dyns in dwfl_segment_report_module
@ 2022-01-06 16:37 Mark Wielaard
0 siblings, 0 replies; only message in thread
From: Mark Wielaard @ 2022-01-06 16:37 UTC (permalink / raw)
To: elfutils-devel; +Cc: Mark Wielaard
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 <mark@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 <mark@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 <mark@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
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