From: Fangrui Song <maskray@google.com> To: Alexander Viro <viro@zeniv.linux.org.uk>, Christian Brauner <brauner@kernel.org>, Eric Biederman <ebiederm@xmission.com>, Kees Cook <keescook@chromium.org>, Baoquan He <bhe@redhat.com>, Vivek Goyal <vgoyal@redhat.com>, Dave Young <dyoung@redhat.com>, linux-fsdevel@vger.kernel.org, kexec@lists.infradead.org Cc: linux-kernel@vger.kernel.org, Fangrui Song <maskray@google.com> Subject: [PATCH] coredump, vmcore: Set p_align to 4 for PT_NOTE Date: Fri, 12 May 2023 02:25:28 +0000 [thread overview] Message-ID: <20230512022528.3430327-1-maskray@google.com> (raw) Tools like readelf/llvm-readelf use p_align to parse a PT_NOTE program header as an array of 4-byte entries or 8-byte entries. Currently, there are workarounds[1] in place for Linux to treat p_align==0 as 4. However, it would be more appropriate to set the correct alignment so that tools do not have to rely on guesswork. FreeBSD coredumps set p_align to 4 as well. [1]: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=82ed9683ec099d8205dc499ac84febc975235af6 [2]: https://reviews.llvm.org/D150022 --- fs/binfmt_elf.c | 2 +- fs/binfmt_elf_fdpic.c | 2 +- fs/proc/vmcore.c | 4 ++-- 3 files changed, 4 insertions(+), 4 deletions(-) diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index 1033fbdfdbec..44b4c42ab8e8 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -1517,7 +1517,7 @@ static void fill_elf_note_phdr(struct elf_phdr *phdr, int sz, loff_t offset) phdr->p_filesz = sz; phdr->p_memsz = 0; phdr->p_flags = 0; - phdr->p_align = 0; + phdr->p_align = 4; } static void fill_note(struct memelfnote *note, const char *name, int type, diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c index 05a1471d5283..d76ad3d4f676 100644 --- a/fs/binfmt_elf_fdpic.c +++ b/fs/binfmt_elf_fdpic.c @@ -1269,7 +1269,7 @@ static inline void fill_elf_note_phdr(struct elf_phdr *phdr, int sz, loff_t offs phdr->p_filesz = sz; phdr->p_memsz = 0; phdr->p_flags = 0; - phdr->p_align = 0; + phdr->p_align = 4; return; } diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c index 03f5963914a1..cb80a7703d58 100644 --- a/fs/proc/vmcore.c +++ b/fs/proc/vmcore.c @@ -877,7 +877,7 @@ static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz, phdr.p_offset = roundup(note_off, PAGE_SIZE); phdr.p_vaddr = phdr.p_paddr = 0; phdr.p_filesz = phdr.p_memsz = phdr_sz; - phdr.p_align = 0; + phdr.p_align = 4; /* Add merged PT_NOTE program header*/ tmp = elfptr + sizeof(Elf64_Ehdr); @@ -1068,7 +1068,7 @@ static int __init merge_note_headers_elf32(char *elfptr, size_t *elfsz, phdr.p_offset = roundup(note_off, PAGE_SIZE); phdr.p_vaddr = phdr.p_paddr = 0; phdr.p_filesz = phdr.p_memsz = phdr_sz; - phdr.p_align = 0; + phdr.p_align = 4; /* Add merged PT_NOTE program header*/ tmp = elfptr + sizeof(Elf32_Ehdr); -- 2.40.1.606.ga4b1b128d6-goog
WARNING: multiple messages have this Message-ID (diff)
From: Fangrui Song <maskray@google.com> To: Alexander Viro <viro@zeniv.linux.org.uk>, Christian Brauner <brauner@kernel.org>, Eric Biederman <ebiederm@xmission.com>, Kees Cook <keescook@chromium.org>, Baoquan He <bhe@redhat.com>, Vivek Goyal <vgoyal@redhat.com>, Dave Young <dyoung@redhat.com>, linux-fsdevel@vger.kernel.org, kexec@lists.infradead.org Cc: linux-kernel@vger.kernel.org, Fangrui Song <maskray@google.com> Subject: [PATCH] coredump, vmcore: Set p_align to 4 for PT_NOTE Date: Fri, 12 May 2023 02:25:28 +0000 [thread overview] Message-ID: <20230512022528.3430327-1-maskray@google.com> (raw) Tools like readelf/llvm-readelf use p_align to parse a PT_NOTE program header as an array of 4-byte entries or 8-byte entries. Currently, there are workarounds[1] in place for Linux to treat p_align==0 as 4. However, it would be more appropriate to set the correct alignment so that tools do not have to rely on guesswork. FreeBSD coredumps set p_align to 4 as well. [1]: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=82ed9683ec099d8205dc499ac84febc975235af6 [2]: https://reviews.llvm.org/D150022 --- fs/binfmt_elf.c | 2 +- fs/binfmt_elf_fdpic.c | 2 +- fs/proc/vmcore.c | 4 ++-- 3 files changed, 4 insertions(+), 4 deletions(-) diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index 1033fbdfdbec..44b4c42ab8e8 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -1517,7 +1517,7 @@ static void fill_elf_note_phdr(struct elf_phdr *phdr, int sz, loff_t offset) phdr->p_filesz = sz; phdr->p_memsz = 0; phdr->p_flags = 0; - phdr->p_align = 0; + phdr->p_align = 4; } static void fill_note(struct memelfnote *note, const char *name, int type, diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c index 05a1471d5283..d76ad3d4f676 100644 --- a/fs/binfmt_elf_fdpic.c +++ b/fs/binfmt_elf_fdpic.c @@ -1269,7 +1269,7 @@ static inline void fill_elf_note_phdr(struct elf_phdr *phdr, int sz, loff_t offs phdr->p_filesz = sz; phdr->p_memsz = 0; phdr->p_flags = 0; - phdr->p_align = 0; + phdr->p_align = 4; return; } diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c index 03f5963914a1..cb80a7703d58 100644 --- a/fs/proc/vmcore.c +++ b/fs/proc/vmcore.c @@ -877,7 +877,7 @@ static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz, phdr.p_offset = roundup(note_off, PAGE_SIZE); phdr.p_vaddr = phdr.p_paddr = 0; phdr.p_filesz = phdr.p_memsz = phdr_sz; - phdr.p_align = 0; + phdr.p_align = 4; /* Add merged PT_NOTE program header*/ tmp = elfptr + sizeof(Elf64_Ehdr); @@ -1068,7 +1068,7 @@ static int __init merge_note_headers_elf32(char *elfptr, size_t *elfsz, phdr.p_offset = roundup(note_off, PAGE_SIZE); phdr.p_vaddr = phdr.p_paddr = 0; phdr.p_filesz = phdr.p_memsz = phdr_sz; - phdr.p_align = 0; + phdr.p_align = 4; /* Add merged PT_NOTE program header*/ tmp = elfptr + sizeof(Elf32_Ehdr); -- 2.40.1.606.ga4b1b128d6-goog _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec
next reply other threads:[~2023-05-12 2:25 UTC|newest] Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-05-12 2:25 Fangrui Song [this message] 2023-05-12 2:25 ` [PATCH] coredump, vmcore: Set p_align to 4 for PT_NOTE Fangrui Song 2023-05-12 18:27 ` Kees Cook 2023-05-12 18:27 ` Kees Cook 2023-05-12 18:39 ` Fangrui Song 2023-05-12 18:39 ` Fangrui Song 2023-05-16 21:32 ` Kees Cook 2023-05-16 21:32 ` Kees Cook
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