Re: [PATCH] libdw: initialize state early in read_srclines

Re: [PATCH] libdw: initialize state early in read_srclines

[Mark Wielaard]

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On Mon, 2015-11-16 at 18:11 +0300, Dmitry V. Levin wrote:
> Starting with commit f8443bd09f8a8d3d84a63e5ce206a218e57dff7a,
> we might jump to "out" on error before initialization of "state".
> Initialize "state" early to fix this issue.

Right, and "out" cleans up using some of the "state" following the
linelist pointer. So we better make sure that is always setup correctly.

Added a ChangeLog entry and applied to master.

Thanks,

Mark

[PATCH] libdw: initialize state early in read_srclines

[Dmitry V. Levin]

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Starting with commit f8443bd09f8a8d3d84a63e5ce206a218e57dff7a,
we might jump to "out" on error before initialization of "state".
Initialize "state" early to fix this issue.

Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
---
 libdw/dwarf_getsrclines.c | 39 ++++++++++++++++++++-------------------
 1 file changed, 20 insertions(+), 19 deletions(-)

diff --git a/libdw/dwarf_getsrclines.c b/libdw/dwarf_getsrclines.c
index 03bdc8f..dd1b3c1 100644
--- a/libdw/dwarf_getsrclines.c
+++ b/libdw/dwarf_getsrclines.c
@@ -185,6 +185,25 @@ read_srclines (Dwarf *dbg,
   struct dirlist dirstack[MAX_STACK_DIRS];
   struct dirlist *dirarray = dirstack;
 
+  /* We are about to process the statement program.  Initialize the
+     state machine registers (see 6.2.2 in the v2.1 specification).  */
+  struct line_state state =
+    {
+      .linelist = NULL,
+      .nlinelist = 0,
+      .addr = 0,
+      .op_index = 0,
+      .file = 1,
+      /* We only store int but want to check for overflow (see SET above).  */
+      .line = 1,
+      .column = 0,
+      .basic_block = false,
+      .prologue_end = false,
+      .epilogue_begin = false,
+      .isa = 0,
+      .discriminator = 0
+    };
+
   if (unlikely (linep + 4 > lineendp))
     {
     invalid_data:
@@ -387,25 +406,7 @@ read_srclines (Dwarf *dbg,
       goto out;
     }
 
-  /* We are about to process the statement program.  Initialize the
-     state machine registers (see 6.2.2 in the v2.1 specification).  */
-  struct line_state state =
-    {
-      .linelist = NULL,
-      .nlinelist = 0,
-      .addr = 0,
-      .op_index = 0,
-      .file = 1,
-      /* We only store int but want to check for overflow (see SET above).  */
-      .line = 1,
-      .column = 0,
-      .is_stmt = default_is_stmt,
-      .basic_block = false,
-      .prologue_end = false,
-      .epilogue_begin = false,
-      .isa = 0,
-      .discriminator = 0
-    };
+  state.is_stmt = default_is_stmt;
 
   /* Apply the "operation advance" from a special opcode or
      DW_LNS_advance_pc (as per DWARF4 6.2.5.1).  */

-- 
ldv