diff options
| author | Mark Wielaard <mark@klomp.org> | 2018-08-04 22:36:48 +0200 |
|---|---|---|
| committer | Mark Wielaard <mark@klomp.org> | 2018-09-14 00:52:48 +0200 |
| commit | eab0cf411128c0130d9284daf3bcd372d5384d3a (patch) | |
| tree | 638a6c1c1e6057bdc55ff310a02a1f3239935433 | |
| parent | 7859092379225482ffd4b49de2d18ad2d69ce810 (diff) | |
libdwfl: Document core memory and remote memory ELF shdrs reading.
There are two places, dwfl_segment_report_module and elf_from_remote_memory
in libdwfl where we use the Ehdr e_shnum directly. Document why this is fine.
Getting the shdrs in those two places is really just a nice bonus and if there
are more than 0xff00 then it is unlikely we will get them all anyway.
Signed-off-by: Mark Wielaard <mark@klomp.org>
| -rw-r--r-- | libdwfl/ChangeLog | 6 | ||||
| -rw-r--r-- | libdwfl/dwfl_segment_report_module.c | 6 | ||||
| -rw-r--r-- | libdwfl/elf-from-memory.c | 6 |
3 files changed, 18 insertions, 0 deletions
diff --git a/libdwfl/ChangeLog b/libdwfl/ChangeLog index 15d75114..5e9b986d 100644 --- a/libdwfl/ChangeLog +++ b/libdwfl/ChangeLog @@ -1,3 +1,9 @@ +2018-09-13 Mark Wielaard <mark@klomp.org> + + * dwfl_segment_report_module.c (dwfl_segment_report_module): + Document why we use e_shnum directly. + * elf-from-memory.c (elf_from_remote_memory): Likewise. + 2018-07-17 Ulf Hermann <ulf.hermann@qt.io> * linux-pid-attach.c: Include sys/uio.h only on linux. diff --git a/libdwfl/dwfl_segment_report_module.c b/libdwfl/dwfl_segment_report_module.c index 207a2573..36e5c823 100644 --- a/libdwfl/dwfl_segment_report_module.c +++ b/libdwfl/dwfl_segment_report_module.c @@ -367,6 +367,11 @@ dwfl_segment_report_module (Dwfl *dwfl, int ndx, const char *name, phentsize = ehdr.e32.e_phentsize; if (phentsize != sizeof (Elf32_Phdr)) return finish (); + /* NOTE if the number of sections is > 0xff00 then e_shnum + is zero and the actual number would come from the section + zero sh_size field. We ignore this here because getting shdrs + is just a nice bonus (see below in consider_phdr PT_LOAD + where we trim the last segment). */ shdrs_end = ehdr.e32.e_shoff + ehdr.e32.e_shnum * ehdr.e32.e_shentsize; break; @@ -380,6 +385,7 @@ dwfl_segment_report_module (Dwfl *dwfl, int ndx, const char *name, phentsize = ehdr.e64.e_phentsize; if (phentsize != sizeof (Elf64_Phdr)) return finish (); + /* See the NOTE above for shdrs_end and ehdr.e32.e_shnum. */ shdrs_end = ehdr.e64.e_shoff + ehdr.e64.e_shnum * ehdr.e64.e_shentsize; break; diff --git a/libdwfl/elf-from-memory.c b/libdwfl/elf-from-memory.c index 12a0a1be..c54c1b99 100644 --- a/libdwfl/elf-from-memory.c +++ b/libdwfl/elf-from-memory.c @@ -139,6 +139,11 @@ elf_from_remote_memory (GElf_Addr ehdr_vma, phentsize = ehdr.e32.e_phentsize; if (phentsize != sizeof (Elf32_Phdr) || phnum == 0) goto bad_elf; + /* NOTE if the number of sections is > 0xff00 then e_shnum + is zero and the actual number would come from the section + zero sh_size field. We ignore this here because getting shdrs + is just a nice bonus (see below where we trim the last phdrs + PT_LOAD segment). */ shdrs_end = ehdr.e32.e_shoff + ehdr.e32.e_shnum * ehdr.e32.e_shentsize; break; @@ -151,6 +156,7 @@ elf_from_remote_memory (GElf_Addr ehdr_vma, phentsize = ehdr.e64.e_phentsize; if (phentsize != sizeof (Elf64_Phdr) || phnum == 0) goto bad_elf; + /* See the NOTE above for shdrs_end and ehdr.e32.e_shnum. */ shdrs_end = ehdr.e64.e_shoff + ehdr.e64.e_shnum * ehdr.e64.e_shentsize; break; |