diff mbox series

libdwfl: Handle unaligned Dyns in dwfl_segment_report_module

Message ID 20220106163717.116122-1-mark@klomp.org
State Committed
Headers show
Series libdwfl: Handle unaligned Dyns in dwfl_segment_report_module | expand

Commit Message

Mark Wielaard Jan. 6, 2022, 4:37 p.m. UTC
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 mbox series

Patch

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))
         {