There was a small memory leak if an error was detected in some places
in dwfl_segment_report_module after the build_id.memory was alredy
allocated. Fix this by moving initialization of struct elf_build_id
early and always free the memory, if not NULL, at exit.
https://sourceware.org/bugzilla/show_bug.cgi?id=28685
Signed-off-by: Mark Wielaard <mark@klomp.org>
---
libdwfl/ChangeLog | 6 ++++++
libdwfl/dwfl_segment_report_module.c | 26 ++++++++++++--------------
2 files changed, 18 insertions(+), 14 deletions(-)
@@ -1,3 +1,9 @@
+2021-12-20 Mark Wielaard <mark@klomp.org>
+
+ * dwfl_segment_report_module.c (dwfl_segment_report_module): Move
+ and initialize struct elf_build_id build_id early. Only free memory
+ early when no longer needed. Free memory if not NULL at out.
+
2021-12-19 Mark Wielaard <mark@klomp.org>
* dwfl_segment_report_module.c (dwfl_segment_report_module): Copy
@@ -1,5 +1,6 @@
/* Sniff out modules from ELF headers visible in memory segments.
Copyright (C) 2008-2012, 2014, 2015, 2018 Red Hat, Inc.
+ Copyright (C) 2021 Mark J. Wielaard <mark@klomp.org>
This file is part of elfutils.
This file is free software; you can redistribute it and/or modify
@@ -332,6 +333,12 @@ dwfl_segment_report_module (Dwfl *dwfl, int ndx, const char *name,
here so we can always safely free it. */
void *phdrsp = NULL;
+ /* Collect the build ID bits here. */
+ struct elf_build_id build_id;
+ build_id.memory = NULL;
+ build_id.len = 0;
+ build_id.vaddr = 0;
+
if (! (*memory_callback) (dwfl, ndx, &buffer, &buffer_available,
start, sizeof (Elf64_Ehdr), memory_callback_arg)
|| memcmp (buffer, ELFMAG, SELFMAG) != 0)
@@ -492,12 +499,6 @@ dwfl_segment_report_module (Dwfl *dwfl, int ndx, const char *name,
GElf_Addr dyn_vaddr = 0;
GElf_Xword dyn_filesz = 0;
- /* Collect the build ID bits here. */
- struct elf_build_id build_id;
- build_id.memory = NULL;
- build_id.len = 0;
- build_id.vaddr =0;
-
Elf32_Phdr *p32 = phdrsp;
Elf64_Phdr *p64 = phdrsp;
if ((ei_class == ELFCLASS32
@@ -701,10 +702,7 @@ dwfl_segment_report_module (Dwfl *dwfl, int ndx, const char *name,
/* We must have seen the segment covering offset 0, or else the ELF
header we read at START was not produced by these program headers. */
if (unlikely (!found_bias))
- {
- free (build_id.memory);
- goto out;
- }
+ goto out;
/* Now we know enough to report a module for sure: its bounds. */
module_start += bias;
@@ -772,10 +770,7 @@ dwfl_segment_report_module (Dwfl *dwfl, int ndx, const char *name,
}
}
if (skip_this_module)
- {
- free (build_id.memory);
- goto out;
- }
+ goto out;
}
const char *file_note_name = handle_file_note (module_start, module_end,
@@ -940,6 +935,7 @@ dwfl_segment_report_module (Dwfl *dwfl, int ndx, const char *name,
/* At this point we do not need BUILD_ID or NAME any more.
They have been copied. */
free (build_id.memory);
+ build_id.memory = NULL;
finish_portion (&read_state, &soname, &soname_size);
if (unlikely (mod == NULL))
@@ -1042,6 +1038,8 @@ dwfl_segment_report_module (Dwfl *dwfl, int ndx, const char *name,
}
out:
+ if (build_id.memory != NULL)
+ free (build_id.memory);
free (phdrsp);
if (buffer != NULL)
(*memory_callback) (dwfl, -1, &buffer, &buffer_available, 0, 0,