From: Philipp Rudo <prudo@linux.vnet.ibm.com> To: kexec@lists.infradead.org, linux-s390@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Eric Biederman <ebiederm@xmission.com>, Vivek Goyal <vgoyal@redhat.com>, Michael Ellerman <mpe@ellerman.id.au>, Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>, Martin Schwidefsky <schwidefsky@de.ibm.com>, Heiko Carstens <heiko.carstens@de.ibm.com>, Andrew Morton <akpm@linux-foundation.org>, x86@kernel.org Subject: [PATCH 09/17] kexec_file: Remove mis-use of sh_offset field Date: Mon, 12 Feb 2018 11:07:46 +0100 [thread overview] Message-ID: <20180212100754.55121-10-prudo@linux.vnet.ibm.com> (raw) In-Reply-To: <20180212100754.55121-1-prudo@linux.vnet.ibm.com> The current code uses the sh_offset field in purgatory_info->sechdrs to store a pointer to the current load address of the section. Depending whether the section will be loaded or not this is either a pointer into purgatory_info->purgatory_buf or kexec_purgatory. This is not only a violation of the ELF standard but also makes the code very hard to understand as you cannot tell if the memory you are using is read-only or not. Remove this mis-use and store the offset of the section in pugaroty_info->purgatory_buf in sh_offset. Signed-off-by: Philipp Rudo <prudo@linux.vnet.ibm.com> --- arch/x86/kernel/machine_kexec_64.c | 10 ++++++---- kernel/kexec_file.c | 33 +++------------------------------ 2 files changed, 9 insertions(+), 34 deletions(-) diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c index 6be04e4d4a7e..cf233e878d28 100644 --- a/arch/x86/kernel/machine_kexec_64.c +++ b/arch/x86/kernel/machine_kexec_64.c @@ -457,13 +457,15 @@ int arch_kexec_apply_relocations_add(struct purgatory_info *pi, * rel[i].r_offset contains byte offset from beginning * of section to the storage unit affected. * - * This is location to update (->sh_offset). This is temporary - * buffer where section is currently loaded. This will finally - * be loaded to a different address later, pointed to by + * This is location to update. This is temporary buffer + * where section is currently loaded. This will finally be + * loaded to a different address later, pointed to by * ->sh_addr. kexec takes care of moving it * (kexec_load_segment()). */ - location = (void *)(section->sh_offset + rel[i].r_offset); + location = pi->purgatory_buf; + location += section->sh_offset; + location += rel[i].r_offset; /* Final address of the location */ address = section->sh_addr + rel[i].r_offset; diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c index 746b91e46e34..25b44d1a664a 100644 --- a/kernel/kexec_file.c +++ b/kernel/kexec_file.c @@ -736,28 +736,6 @@ static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi, pi->ehdr->e_shnum * sizeof(Elf_Shdr)); pi->sechdrs = sechdrs; - /* - * We seem to have multiple copies of sections. First copy is which - * is embedded in kernel in read only section. Some of these sections - * will be copied to a temporary buffer and relocated. And these - * sections will finally be copied to their final destination at - * segment load time. - * - * Use ->sh_offset to reflect section address in memory. It will - * point to original read only copy if section is not allocatable. - * Otherwise it will point to temporary copy which will be relocated. - * - * Use ->sh_addr to contain final address of the section where it - * will go during execution time. - */ - for (i = 0; i < pi->ehdr->e_shnum; i++) { - if (sechdrs[i].sh_type == SHT_NOBITS) - continue; - - sechdrs[i].sh_offset = (unsigned long)pi->ehdr + - sechdrs[i].sh_offset; - } - offset = 0; bss_addr = kbuf->mem + kbuf->bufsz; kbuf->image->start = pi->ehdr->e_entry; @@ -786,17 +764,12 @@ static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi, kbuf->image->start += kbuf->mem + offset; } - src = (void *)sechdrs[i].sh_offset; + src = (void *)pi->ehdr + sechdrs[i].sh_offset; dst = pi->purgatory_buf + offset; memcpy(dst, src, sechdrs[i].sh_size); sechdrs[i].sh_addr = kbuf->mem + offset; - - /* - * This section got copied to temporary buffer. Update - * ->sh_offset accordingly. - */ - sechdrs[i].sh_offset = (unsigned long)dst; + sechdrs[i].sh_offset = offset; offset += sechdrs[i].sh_size; } @@ -1006,7 +979,7 @@ int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name, return -EINVAL; } - sym_buf = (char *)sec->sh_offset + sym->st_value; + sym_buf = (char *)pi->purgatory_buf + sec->sh_offset + sym->st_value; if (get_value) memcpy((void *)buf, sym_buf, size); -- 2.13.5
WARNING: multiple messages have this Message-ID (diff)
From: Philipp Rudo <prudo@linux.vnet.ibm.com> To: kexec@lists.infradead.org, linux-s390@vger.kernel.org Cc: Michael Ellerman <mpe@ellerman.id.au>, x86@kernel.org, Heiko Carstens <heiko.carstens@de.ibm.com>, linux-kernel@vger.kernel.org, Martin Schwidefsky <schwidefsky@de.ibm.com>, Eric Biederman <ebiederm@xmission.com>, Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>, Andrew Morton <akpm@linux-foundation.org>, Vivek Goyal <vgoyal@redhat.com> Subject: [PATCH 09/17] kexec_file: Remove mis-use of sh_offset field Date: Mon, 12 Feb 2018 11:07:46 +0100 [thread overview] Message-ID: <20180212100754.55121-10-prudo@linux.vnet.ibm.com> (raw) In-Reply-To: <20180212100754.55121-1-prudo@linux.vnet.ibm.com> The current code uses the sh_offset field in purgatory_info->sechdrs to store a pointer to the current load address of the section. Depending whether the section will be loaded or not this is either a pointer into purgatory_info->purgatory_buf or kexec_purgatory. This is not only a violation of the ELF standard but also makes the code very hard to understand as you cannot tell if the memory you are using is read-only or not. Remove this mis-use and store the offset of the section in pugaroty_info->purgatory_buf in sh_offset. Signed-off-by: Philipp Rudo <prudo@linux.vnet.ibm.com> --- arch/x86/kernel/machine_kexec_64.c | 10 ++++++---- kernel/kexec_file.c | 33 +++------------------------------ 2 files changed, 9 insertions(+), 34 deletions(-) diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c index 6be04e4d4a7e..cf233e878d28 100644 --- a/arch/x86/kernel/machine_kexec_64.c +++ b/arch/x86/kernel/machine_kexec_64.c @@ -457,13 +457,15 @@ int arch_kexec_apply_relocations_add(struct purgatory_info *pi, * rel[i].r_offset contains byte offset from beginning * of section to the storage unit affected. * - * This is location to update (->sh_offset). This is temporary - * buffer where section is currently loaded. This will finally - * be loaded to a different address later, pointed to by + * This is location to update. This is temporary buffer + * where section is currently loaded. This will finally be + * loaded to a different address later, pointed to by * ->sh_addr. kexec takes care of moving it * (kexec_load_segment()). */ - location = (void *)(section->sh_offset + rel[i].r_offset); + location = pi->purgatory_buf; + location += section->sh_offset; + location += rel[i].r_offset; /* Final address of the location */ address = section->sh_addr + rel[i].r_offset; diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c index 746b91e46e34..25b44d1a664a 100644 --- a/kernel/kexec_file.c +++ b/kernel/kexec_file.c @@ -736,28 +736,6 @@ static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi, pi->ehdr->e_shnum * sizeof(Elf_Shdr)); pi->sechdrs = sechdrs; - /* - * We seem to have multiple copies of sections. First copy is which - * is embedded in kernel in read only section. Some of these sections - * will be copied to a temporary buffer and relocated. And these - * sections will finally be copied to their final destination at - * segment load time. - * - * Use ->sh_offset to reflect section address in memory. It will - * point to original read only copy if section is not allocatable. - * Otherwise it will point to temporary copy which will be relocated. - * - * Use ->sh_addr to contain final address of the section where it - * will go during execution time. - */ - for (i = 0; i < pi->ehdr->e_shnum; i++) { - if (sechdrs[i].sh_type == SHT_NOBITS) - continue; - - sechdrs[i].sh_offset = (unsigned long)pi->ehdr + - sechdrs[i].sh_offset; - } - offset = 0; bss_addr = kbuf->mem + kbuf->bufsz; kbuf->image->start = pi->ehdr->e_entry; @@ -786,17 +764,12 @@ static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi, kbuf->image->start += kbuf->mem + offset; } - src = (void *)sechdrs[i].sh_offset; + src = (void *)pi->ehdr + sechdrs[i].sh_offset; dst = pi->purgatory_buf + offset; memcpy(dst, src, sechdrs[i].sh_size); sechdrs[i].sh_addr = kbuf->mem + offset; - - /* - * This section got copied to temporary buffer. Update - * ->sh_offset accordingly. - */ - sechdrs[i].sh_offset = (unsigned long)dst; + sechdrs[i].sh_offset = offset; offset += sechdrs[i].sh_size; } @@ -1006,7 +979,7 @@ int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name, return -EINVAL; } - sym_buf = (char *)sec->sh_offset + sym->st_value; + sym_buf = (char *)pi->purgatory_buf + sec->sh_offset + sym->st_value; if (get_value) memcpy((void *)buf, sym_buf, size); -- 2.13.5 _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec
next prev parent reply other threads:[~2018-02-12 10:08 UTC|newest] Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-02-12 10:07 [PATCH 00/17] Add kexec_file_load support to s390 Philipp Rudo 2018-02-12 10:07 ` Philipp Rudo 2018-02-12 10:07 ` [PATCH 01/17] kexec_file: Silence compile warnings Philipp Rudo 2018-02-12 10:07 ` Philipp Rudo 2018-02-12 10:07 ` [PATCH 02/17] kexec_file: Remove checks in kexec_purgatory_load Philipp Rudo 2018-02-12 10:07 ` Philipp Rudo 2018-02-12 10:07 ` [PATCH 03/17] kexec_file: Make purgatory_info->ehdr const Philipp Rudo 2018-02-12 10:07 ` Philipp Rudo 2018-02-12 10:07 ` [PATCH 04/17] kexec_file: Search symbols in read-only kexec_purgatory Philipp Rudo 2018-02-12 10:07 ` Philipp Rudo 2018-02-12 10:07 ` [PATCH 05/17] kexec_file: Use read-only sections in arch_kexec_apply_relocations* Philipp Rudo 2018-02-12 10:07 ` Philipp Rudo 2018-02-12 10:07 ` [PATCH 06/17] kexec_file: Split up __kexec_load_puragory Philipp Rudo 2018-02-12 10:07 ` Philipp Rudo 2018-02-12 10:07 ` [PATCH 07/17] kexec_file: Simplify kexec_purgatory_setup_sechdrs 1 Philipp Rudo 2018-02-12 10:07 ` Philipp Rudo 2018-02-12 10:07 ` [PATCH 08/17] kexec_file: Simplify kexec_purgatory_setup_sechdrs 2 Philipp Rudo 2018-02-12 10:07 ` Philipp Rudo 2018-02-12 10:07 ` Philipp Rudo [this message] 2018-02-12 10:07 ` [PATCH 09/17] kexec_file: Remove mis-use of sh_offset field Philipp Rudo 2018-02-12 10:07 ` [PATCH 10/17] kexec_file: Allow archs to set purgatory load address Philipp Rudo 2018-02-12 10:07 ` Philipp Rudo 2018-02-12 10:07 ` [PATCH 11/17] kexec_file: Move purgatories sha256 to common code Philipp Rudo 2018-02-12 10:07 ` Philipp Rudo 2018-02-12 10:07 ` [PATCH 12/17] s390/kexec_file: Prepare setup.h for kexec_file_load Philipp Rudo 2018-02-12 10:07 ` Philipp Rudo 2018-02-12 10:07 ` [PATCH 13/17] s390/kexec_file: Add purgatory Philipp Rudo 2018-02-12 10:07 ` Philipp Rudo 2018-02-12 10:07 ` [PATCH 14/17] s390/kexec_file: Add kexec_file_load system call Philipp Rudo 2018-02-12 10:07 ` Philipp Rudo 2018-02-12 10:56 ` Philippe Ombredanne 2018-02-12 10:56 ` Philippe Ombredanne 2018-02-12 11:29 ` Philipp Rudo 2018-02-12 11:29 ` Philipp Rudo 2018-02-12 10:07 ` [PATCH 15/17] s390/kexec_file: Add image loader Philipp Rudo 2018-02-12 10:07 ` Philipp Rudo 2018-02-12 10:07 ` [PATCH 16/17] s390/kexec_file: Add crash support to " Philipp Rudo 2018-02-12 10:07 ` Philipp Rudo 2018-02-12 10:07 ` [PATCH 17/17] s390/kexec_file: Add ELF loader Philipp Rudo 2018-02-12 10:07 ` Philipp Rudo 2018-02-14 7:35 ` [PATCH 00/17] Add kexec_file_load support to s390 Dave Young 2018-02-14 7:35 ` Dave Young 2018-02-14 7:35 ` Dave Young 2018-02-14 9:54 ` Philipp Rudo 2018-02-14 9:54 ` Philipp Rudo 2018-02-15 5:08 ` AKASHI Takahiro 2018-02-15 5:08 ` AKASHI Takahiro 2018-02-23 8:34 ` Dave Young 2018-02-23 8:34 ` Dave Young 2018-02-23 10:01 ` Philipp Rudo 2018-02-23 10:01 ` Philipp Rudo 2018-02-24 1:59 ` Dave Young 2018-02-24 1:59 ` Dave Young 2018-02-26 1:21 ` AKASHI Takahiro 2018-02-26 1:21 ` AKASHI Takahiro 2018-02-26 11:16 ` Philipp Rudo 2018-02-26 11:16 ` Philipp Rudo -- strict thread matches above, loose matches on Subject: below -- 2018-02-02 13:07 Philipp Rudo 2018-02-02 13:07 ` [PATCH 09/17] kexec_file: Remove mis-use of sh_offset field Philipp Rudo 2018-02-02 13:07 ` Philipp Rudo
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