From: Di Chen <dichen@redhat.com>
To: elfutils-devel@sourceware.org
Subject: Re: [PATCH] readelf: PR28928 - wrong dynamic section entry number
Date: Wed, 30 Mar 2022 19:25:58 +0800 [thread overview]
Message-ID: <CAN-Pu7RgEzoXd2cbpUKAYr8-UEg1Li5cYShaP-yYRzEmd8X+kg@mail.gmail.com> (raw)
In-Reply-To: <CAN-Pu7Q0AAYtPgmJ8zZAFJ4yq5UYTMxPnHmjNGHbOoXRdpkHTA@mail.gmail.com>
From b0da0a6f6c9a57a37a144a806ecd219a76c66b54 Mon Sep 17 00:00:00 2001
From: Di Chen <dichen@redhat.com>
Date: Tue, 1 Mar 2022 20:44:38 +0800
Subject: [PATCH] readelf: Don't consider padding DT_NULL as dynamic section
entry
when using `$ eu-readelf -d {FILE}` to get the number of dynamic
section entris, it wrongly counts the padding DT_NULLs as dynamic
section entries. However, DT_NULL Marks end of dynamic section.
They should not be considered as dynamic section entries.
https://sourceware.org/bugzilla/show_bug.cgi?id=28928
Signed-off-by: Di Chen <dichen@redhat.com>
---
src/readelf.c | 49 ++++++++++++++++++++++++++++++++++++------
tests/alldts.c | 5 +++--
tests/run-alldts.sh | 2 +-
tests/run-readelf-d.sh | 7 +-----
4 files changed, 48 insertions(+), 15 deletions(-)
diff --git a/src/readelf.c b/src/readelf.c
index 93fb5989..0d70bb47 100644
--- a/src/readelf.c
+++ b/src/readelf.c
@@ -296,6 +296,7 @@ static void print_shdr (Ebl *ebl, GElf_Ehdr *ehdr);
static void print_phdr (Ebl *ebl, GElf_Ehdr *ehdr);
static void print_scngrp (Ebl *ebl);
static void print_dynamic (Ebl *ebl);
+static void handle_dynamic (Ebl *ebl, Elf_Scn *scn, GElf_Shdr *shdr);
static void print_relocs (Ebl *ebl, GElf_Ehdr *ehdr);
static void handle_relocs_rel (Ebl *ebl, GElf_Ehdr *ehdr, Elf_Scn *scn,
GElf_Shdr *shdr);
@@ -1781,16 +1782,54 @@ print_dt_posflag_1 (int class, GElf_Xword d_val)
}
+static GElf_Phdr *
+get_dyn_phdr (Elf *elf)
+{
+ GElf_Phdr *phdr = NULL;
+ for (size_t i = 0; i < phnum; ++i) {
+ GElf_Phdr phdr_mem;
+ phdr = gelf_getphdr(elf, i, &phdr_mem);
+ if (phdr->p_type == PT_DYNAMIC) {
+ break;
+ }
+ }
+ return phdr;
+}
+
+
+static size_t
+get_dyn_scnents (Elf *elf, GElf_Phdr * dyn_phdr)
+{
+ Elf_Data *data = elf_getdata_rawchunk(
+ elf, dyn_phdr->p_offset, dyn_phdr->p_filesz, ELF_T_DYN);
+ GElf_Dyn *dyn;
+ size_t dyn_idx = 0;
+ do
+ {
+ GElf_Dyn dyn_mem;
+ dyn = gelf_getdyn(data, dyn_idx, &dyn_mem);
+ ++dyn_idx;
+ } while (dyn->d_tag != DT_NULL);
+
+ return dyn_idx;
+}
+
+
static void
handle_dynamic (Ebl *ebl, Elf_Scn *scn, GElf_Shdr *shdr)
{
int class = gelf_getclass (ebl->elf);
+ GElf_Phdr *dyn_phdr;
GElf_Shdr glink_mem;
GElf_Shdr *glink;
Elf_Data *data;
size_t cnt;
size_t shstrndx;
- size_t sh_entsize;
+ size_t dyn_scnents;
+
+ /* Get the dynamic section entry number */
+ dyn_phdr = get_dyn_phdr (ebl->elf);
+ dyn_scnents = get_dyn_scnents (ebl->elf, dyn_phdr);
/* Get the data of the section. */
data = elf_getdata (scn, NULL);
@@ -1802,8 +1841,6 @@ handle_dynamic (Ebl *ebl, Elf_Scn *scn, GElf_Shdr
*shdr)
error (EXIT_FAILURE, 0,
_("cannot get section header string table index"));
- sh_entsize = gelf_fsize (ebl->elf, ELF_T_DYN, 1, EV_CURRENT);
-
glink = gelf_getshdr (elf_getscn (ebl->elf, shdr->sh_link), &glink_mem);
if (glink == NULL)
error (EXIT_FAILURE, 0, _("invalid sh_link value in section %zu"),
@@ -1813,15 +1850,15 @@ handle_dynamic (Ebl *ebl, Elf_Scn *scn, GElf_Shdr
*shdr)
\nDynamic segment contains %lu entry:\n Addr: %#0*" PRIx64 " Offset:
%#08" PRIx64 " Link to section: [%2u] '%s'\n",
"\
\nDynamic segment contains %lu entries:\n Addr: %#0*" PRIx64 " Offset:
%#08" PRIx64 " Link to section: [%2u] '%s'\n",
- shdr->sh_size / sh_entsize),
- (unsigned long int) (shdr->sh_size / sh_entsize),
+ dyn_scnents),
+ (unsigned long int) dyn_scnents,
class == ELFCLASS32 ? 10 : 18, shdr->sh_addr,
shdr->sh_offset,
(int) shdr->sh_link,
elf_strptr (ebl->elf, shstrndx, glink->sh_name));
fputs_unlocked (_(" Type Value\n"), stdout);
- for (cnt = 0; cnt < shdr->sh_size / sh_entsize; ++cnt)
+ for (cnt = 0; cnt < dyn_scnents; ++cnt)
{
GElf_Dyn dynmem;
GElf_Dyn *dyn = gelf_getdyn (data, cnt, &dynmem);
diff --git a/tests/alldts.c b/tests/alldts.c
index 3e9f9fe6..d0fe4f24 100644
--- a/tests/alldts.c
+++ b/tests/alldts.c
@@ -44,7 +44,7 @@ main (void)
Dwelf_Strent *shstrtabse;
const Elf32_Sword dtflags[] =
{
- DT_NULL, DT_NEEDED, DT_PLTRELSZ, DT_PLTGOT,
+ DT_NEEDED, DT_PLTRELSZ, DT_PLTGOT,
DT_HASH, DT_STRTAB, DT_SYMTAB, DT_RELA,
DT_RELASZ, DT_RELAENT, DT_STRSZ, DT_SYMENT,
DT_INIT, DT_FINI, DT_SONAME, DT_RPATH,
@@ -61,7 +61,8 @@ main (void)
DT_GNU_LIBLIST, DT_CONFIG, DT_DEPAUDIT, DT_AUDIT,
DT_PLTPAD, DT_MOVETAB, DT_SYMINFO, DT_RELACOUNT,
DT_RELCOUNT, DT_FLAGS_1, DT_VERDEF, DT_VERDEFNUM,
- DT_VERNEED, DT_VERNEEDNUM, DT_AUXILIARY, DT_FILTER
+ DT_VERNEED, DT_VERNEEDNUM, DT_AUXILIARY, DT_FILTER,
+ DT_NULL
};
const int ndtflags = sizeof (dtflags) / sizeof (dtflags[0]);
diff --git a/tests/run-alldts.sh b/tests/run-alldts.sh
index 6a9a9ece..ce3630b0 100755
--- a/tests/run-alldts.sh
+++ b/tests/run-alldts.sh
@@ -27,7 +27,6 @@ testrun_compare ${abs_top_builddir}/src/readelf -d
testfile-alldts <<\EOF
Dynamic segment contains 66 entries:
Addr: 0x000001a0 Offset: 0x000078 Link to section: [ 0] ''
Type Value
- NULL
NEEDED Shared library: [(null)]
PLTRELSZ 3735928559 (bytes)
PLTGOT 0xdeadbeef
@@ -93,6 +92,7 @@ Dynamic segment contains 66 entries:
VERNEEDNUM 3735928559
AUXILIARY 0xdeadbeef
FILTER 0xdeadbeef
+ NULL
EOF
exit 0
diff --git a/tests/run-readelf-d.sh b/tests/run-readelf-d.sh
index d0b6ed24..69b01c49 100755
--- a/tests/run-readelf-d.sh
+++ b/tests/run-readelf-d.sh
@@ -34,7 +34,7 @@ testfiles testlib_dynseg.so
testrun_compare ${abs_top_builddir}/src/readelf -d testlib_dynseg.so <<\EOF
-Dynamic segment contains 28 entries:
+Dynamic segment contains 23 entries:
Addr: 0x00000000000017e0 Offset: 0x0007e0 Link to section: [ 3]
'.dynstr'
Type Value
PLTGOT 0x00000000000019c8
@@ -60,11 +60,6 @@ Dynamic segment contains 28 entries:
VERNEED 0x0000000000000498
VERNEEDNUM 2
NULL
- NULL
- NULL
- NULL
- NULL
- NULL
EOF
exit 0
--
2.35.1
On Tue, Mar 22, 2022 at 9:47 PM Di Chen <dichen@redhat.com> wrote:
> Hey team,
> I made some changes for this patch:
> (1) update the commit message to make it more clear
> (2) tests/alldts.c needs the padding spaces for output comparison
>
> On Tue, Mar 1, 2022 at 8:54 PM Di Chen <dichen@redhat.com> wrote:
>
>> commit 978663c5323cf402cd35b8614e41f24b587cbdd8 (HEAD -> dichen/DT_NULL,
>> origin/dichen/DT_NULL)
>> Author: Di Chen <dichen@redhat.com>
>> Date: Tue Mar 1 20:44:38 2022 +0800
>>
>> readelf: PR28928 - wrong dynamic section entry number
>>
>> when using `$ eu-readelf -d {file}` to get the number of dynamic
>> section entris, It wrongly counts the padding DT_NULLs as dynamic
>> section entries. However, DT_NULL Marks end of dynamic section.
>> They should not be counted as dynamic section entries.
>>
>> https://sourceware.org/bugzilla/show_bug.cgi?id=28928
>>
>> Signed-off-by: Di Chen <dichen@redhat.com>
>>
>> diff --git a/src/readelf.c b/src/readelf.c
>> index 93fb5989..1bec3aa6 100644
>> --- a/src/readelf.c
>> +++ b/src/readelf.c
>> @@ -296,6 +296,7 @@ static void print_shdr (Ebl *ebl, GElf_Ehdr *ehdr);
>> static void print_phdr (Ebl *ebl, GElf_Ehdr *ehdr);
>> static void print_scngrp (Ebl *ebl);
>> static void print_dynamic (Ebl *ebl);
>> +static void handle_dynamic (Ebl *ebl, Elf_Scn *scn, GElf_Shdr *shdr);
>> static void print_relocs (Ebl *ebl, GElf_Ehdr *ehdr);
>> static void handle_relocs_rel (Ebl *ebl, GElf_Ehdr *ehdr, Elf_Scn *scn,
>> GElf_Shdr *shdr);
>> @@ -1781,16 +1782,54 @@ print_dt_posflag_1 (int class, GElf_Xword d_val)
>> [dichen@arpeggio elfutils]$ git format-patch -1 HEAD
>> 0001-readelf-PR28928-wrong-dynamic-section-entry-number.patch
>> [dichen@arpeggio elfutils]$ vim
>> 0001-readelf-PR28928-wrong-dynamic-section-entry-number.patch
>> [dichen@arpeggio elfutils]$ cat
>> 0001-readelf-PR28928-wrong-dynamic-section-entry-number.patch
>> From 978663c5323cf402cd35b8614e41f24b587cbdd8 Mon Sep 17 00:00:00 2001
>> From: Di Chen <dichen@redhat.com>
>> Date: Tue, 1 Mar 2022 20:44:38 +0800
>> Subject: [PATCH] readelf: PR28928 - wrong dynamic section entry number
>>
>> when using `$ eu-readelf -d {file}` to get the number of dynamic
>> section entris, It wrongly counts the padding DT_NULLs as dynamic
>> section entries. However, DT_NULL Marks end of dynamic section.
>> They should not be counted as dynamic section entries.
>>
>> https://sourceware.org/bugzilla/show_bug.cgi?id=28928
>>
>> Signed-off-by: Di Chen <dichen@redhat.com>
>> ---
>> src/readelf.c | 49 ++++++++++++++++++++++++++++++++++++------
>> tests/alldts.c | 5 +++--
>> tests/run-alldts.sh | 2 +-
>> tests/run-readelf-d.sh | 7 +-----
>> 4 files changed, 48 insertions(+), 15 deletions(-)
>>
>> diff --git a/src/readelf.c b/src/readelf.c
>> index 93fb5989..1bec3aa6 100644
>> --- a/src/readelf.c
>> +++ b/src/readelf.c
>> @@ -296,6 +296,7 @@ static void print_shdr (Ebl *ebl, GElf_Ehdr *ehdr);
>> static void print_phdr (Ebl *ebl, GElf_Ehdr *ehdr);
>> static void print_scngrp (Ebl *ebl);
>> static void print_dynamic (Ebl *ebl);
>> +static void handle_dynamic (Ebl *ebl, Elf_Scn *scn, GElf_Shdr *shdr);
>> static void print_relocs (Ebl *ebl, GElf_Ehdr *ehdr);
>> static void handle_relocs_rel (Ebl *ebl, GElf_Ehdr *ehdr, Elf_Scn *scn,
>> GElf_Shdr *shdr);
>> @@ -1781,16 +1782,54 @@ print_dt_posflag_1 (int class, GElf_Xword d_val)
>> }
>>
>>
>> +static GElf_Phdr *
>> +get_dyn_phdr (Elf *elf)
>> +{
>> + GElf_Phdr *phdr = NULL;
>> + for (size_t i = 0; i < phnum; ++i) {
>> + GElf_Phdr phdr_mem;
>> + phdr = gelf_getphdr(elf, i, &phdr_mem);
>> + if (phdr->p_type == PT_DYNAMIC) {
>> + break;
>> + }
>> + }
>> + return phdr;
>> +}
>> +
>> +
>> +static size_t
>> +get_dyn_scnents (Elf *elf, GElf_Phdr * dyn_phdr)
>> +{
>> + Elf_Data *data = elf_getdata_rawchunk(
>> + elf, dyn_phdr->p_offset, dyn_phdr->p_filesz, ELF_T_DYN);
>> + GElf_Dyn *dyn;
>> + size_t dyn_idx = 0;
>> + do
>> + {
>> + GElf_Dyn dyn_mem;
>> + dyn = gelf_getdyn(data, dyn_idx, &dyn_mem);
>> + ++dyn_idx;
>> + } while (dyn->d_tag != DT_NULL);
>> +
>> + return dyn_idx;
>> +}
>> +
>> +
>> static void
>> handle_dynamic (Ebl *ebl, Elf_Scn *scn, GElf_Shdr *shdr)
>> {
>> int class = gelf_getclass (ebl->elf);
>> + GElf_Phdr *dyn_phdr;
>> GElf_Shdr glink_mem;
>> GElf_Shdr *glink;
>> Elf_Data *data;
>> size_t cnt;
>> size_t shstrndx;
>> - size_t sh_entsize;
>> + size_t dyn_scnents;
>> +
>> + /* Calculate the dynamic section entry number */
>> + dyn_phdr = get_dyn_phdr (ebl->elf);
>> + dyn_scnents = get_dyn_scnents (ebl->elf, dyn_phdr);
>>
>> /* Get the data of the section. */
>> data = elf_getdata (scn, NULL);
>> @@ -1802,8 +1841,6 @@ handle_dynamic (Ebl *ebl, Elf_Scn *scn, GElf_Shdr
>> *shdr)
>> error (EXIT_FAILURE, 0,
>> _("cannot get section header string table index"));
>>
>> - sh_entsize = gelf_fsize (ebl->elf, ELF_T_DYN, 1, EV_CURRENT);
>> -
>> glink = gelf_getshdr (elf_getscn (ebl->elf, shdr->sh_link),
>> &glink_mem);
>> if (glink == NULL)
>> error (EXIT_FAILURE, 0, _("invalid sh_link value in section %zu"),
>> @@ -1813,15 +1850,15 @@ handle_dynamic (Ebl *ebl, Elf_Scn *scn, GElf_Shdr
>> *shdr)
>> \nDynamic segment contains %lu entry:\n Addr: %#0*" PRIx64 " Offset:
>> %#08" PRIx64 " Link to section: [%2u] '%s'\n",
>> "\
>> \nDynamic segment contains %lu entries:\n Addr: %#0*" PRIx64 " Offset:
>> %#08" PRIx64 " Link to section: [%2u] '%s'\n",
>> - shdr->sh_size / sh_entsize),
>> - (unsigned long int) (shdr->sh_size / sh_entsize),
>> + dyn_scnents),
>> + (unsigned long int) dyn_scnents,
>> class == ELFCLASS32 ? 10 : 18, shdr->sh_addr,
>> shdr->sh_offset,
>> (int) shdr->sh_link,
>> elf_strptr (ebl->elf, shstrndx, glink->sh_name));
>> fputs_unlocked (_(" Type Value\n"), stdout);
>>
>> - for (cnt = 0; cnt < shdr->sh_size / sh_entsize; ++cnt)
>> + for (cnt = 0; cnt < dyn_scnents; ++cnt)
>> {
>> GElf_Dyn dynmem;
>> GElf_Dyn *dyn = gelf_getdyn (data, cnt, &dynmem);
>> diff --git a/tests/alldts.c b/tests/alldts.c
>> index 3e9f9fe6..d0fe4f24 100644
>> --- a/tests/alldts.c
>> +++ b/tests/alldts.c
>> @@ -44,7 +44,7 @@ main (void)
>> Dwelf_Strent *shstrtabse;
>> const Elf32_Sword dtflags[] =
>> {
>> - DT_NULL, DT_NEEDED, DT_PLTRELSZ, DT_PLTGOT,
>> + DT_NEEDED, DT_PLTRELSZ, DT_PLTGOT,
>> DT_HASH, DT_STRTAB, DT_SYMTAB, DT_RELA,
>> DT_RELASZ, DT_RELAENT, DT_STRSZ, DT_SYMENT,
>> DT_INIT, DT_FINI, DT_SONAME, DT_RPATH,
>> @@ -61,7 +61,8 @@ main (void)
>> DT_GNU_LIBLIST, DT_CONFIG, DT_DEPAUDIT, DT_AUDIT,
>> DT_PLTPAD, DT_MOVETAB, DT_SYMINFO, DT_RELACOUNT,
>> DT_RELCOUNT, DT_FLAGS_1, DT_VERDEF, DT_VERDEFNUM,
>> - DT_VERNEED, DT_VERNEEDNUM, DT_AUXILIARY, DT_FILTER
>> + DT_VERNEED, DT_VERNEEDNUM, DT_AUXILIARY, DT_FILTER,
>> + DT_NULL
>> };
>> const int ndtflags = sizeof (dtflags) / sizeof (dtflags[0]);
>>
>> diff --git a/tests/run-alldts.sh b/tests/run-alldts.sh
>> index 6a9a9ece..bd750a35 100755
>> --- a/tests/run-alldts.sh
>> +++ b/tests/run-alldts.sh
>> @@ -27,7 +27,6 @@ testrun_compare ${abs_top_builddir}/src/readelf -d
>> testfile-alldts <<\EOF
>> Dynamic segment contains 66 entries:
>> Addr: 0x000001a0 Offset: 0x000078 Link to section: [ 0] ''
>> Type Value
>> - NULL
>> NEEDED Shared library: [(null)]
>> PLTRELSZ 3735928559 (bytes)
>> PLTGOT 0xdeadbeef
>> @@ -93,6 +92,7 @@ Dynamic segment contains 66 entries:
>> VERNEEDNUM 3735928559
>> AUXILIARY 0xdeadbeef
>> FILTER 0xdeadbeef
>> + NULL
>> EOF
>>
>> exit 0
>> diff --git a/tests/run-readelf-d.sh b/tests/run-readelf-d.sh
>> index d0b6ed24..69b01c49 100755
>> --- a/tests/run-readelf-d.sh
>> +++ b/tests/run-readelf-d.sh
>> @@ -34,7 +34,7 @@ testfiles testlib_dynseg.so
>>
>> testrun_compare ${abs_top_builddir}/src/readelf -d testlib_dynseg.so
>> <<\EOF
>>
>> -Dynamic segment contains 28 entries:
>> +Dynamic segment contains 23 entries:
>> Addr: 0x00000000000017e0 Offset: 0x0007e0 Link to section: [ 3]
>> '.dynstr'
>> Type Value
>> PLTGOT 0x00000000000019c8
>> @@ -60,11 +60,6 @@ Dynamic segment contains 28 entries:
>> VERNEED 0x0000000000000498
>> VERNEEDNUM 2
>> NULL
>> - NULL
>> - NULL
>> - NULL
>> - NULL
>> - NULL
>> EOF
>>
>> exit 0
>> --
>> 2.34.1
>>
>>
prev parent reply other threads:[~2022-03-30 11:26 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-01 12:54 Di Chen
2022-03-22 13:47 ` Di Chen
2022-03-30 11:25 ` Di Chen [this message]
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