[PATCH] Fix section corruption bug

[Thilo Schulz <thilo@tjps.eu>]

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Hi,

When adding data to existing sections in ELF files, libelf may corrupt
those sections, i.e. overwrite the existing data if certain conditions are
met.

If an Elf_Scn structure has seen a call to elf_rawdata(scn) before but no
call to elf_getdata(scn), scn->read_data flag is set, but not
scn->data_list_rear.
Thus, elf_newdata(scn) incorrectly detects a "new user added section" when
really it is a section with live, valid data that will be overwritten by
elf_update(), corrupting the section.

This patch fixes this incorrect behaviour.

Signed-off-by: Thilo Schulz <thilo@tjps.eu>
---
 libelf/elf_newdata.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libelf/elf_newdata.c b/libelf/elf_newdata.c
index 90d1813..f90eb0a 100644
--- a/libelf/elf_newdata.c
+++ b/libelf/elf_newdata.c
@@ -64,7 +64,7 @@ elf_newdata (Elf_Scn *scn)
 
   rwlock_wrlock (scn->elf->lock);
 
-  if (scn->data_read && scn->data_list_rear == NULL)
+  if (scn->data_read && scn->data_list_rear == NULL && !scn->rawdata.s)
     {
       /* This means the section was created by the user and this is the
 	 first data.  */
-- 
1.7.10.4