Date: Sun, 22 Mar 2009 13:42:41 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r190264 - head/sys/kern Message-ID: <200903221342.n2MDgfkt069985@svn.freebsd.org>
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Author: kib Date: Sun Mar 22 13:42:41 2009 New Revision: 190264 URL: http://svn.freebsd.org/changeset/base/190264 Log: Fix several issues with parsing the notes for ELF objects. Badly formed ELF note may cause the caclulated pointer to the next note to point both after the note region, that was checked in the code, but also to point before the region, that was not checked [1]. Remember the first note location in note0 and leap out if the note is not between note0 and note_end. In the similar way, badly formed note may cause infinite loop by pointing next note into the same or previous note. Guard against this by limiting amount of loop iterations by arbitrary choosen big number. For clarity, check the calculated note alignment in each iteration. Reported by: Chris Palmer <chris noncombatant org> [1] PR: kern/132886 Reviewed and tested by: dchagin MFC after: 3 days Modified: head/sys/kern/imgact_elf.c Modified: head/sys/kern/imgact_elf.c ============================================================================== --- head/sys/kern/imgact_elf.c Sun Mar 22 13:17:46 2009 (r190263) +++ head/sys/kern/imgact_elf.c Sun Mar 22 13:42:41 2009 (r190264) @@ -1331,7 +1331,7 @@ static boolean_t __elfN(check_note)(struct image_params *imgp, Elf_Brandnote *checknote, int32_t *osrel) { - const Elf_Note *note, *note_end; + const Elf_Note *note, *note0, *note_end; const Elf_Phdr *phdr, *pnote; const Elf_Ehdr *hdr; const char *note_name; @@ -1352,12 +1352,12 @@ __elfN(check_note)(struct image_params * pnote->p_offset + pnote->p_filesz >= PAGE_SIZE) return (FALSE); - note = (const Elf_Note *)(imgp->image_header + pnote->p_offset); - if (!aligned(note, Elf32_Addr)) - return (FALSE); + note = note0 = (const Elf_Note *)(imgp->image_header + pnote->p_offset); note_end = (const Elf_Note *)(imgp->image_header + pnote->p_offset + pnote->p_filesz); - while (note < note_end) { + for (i = 0; i < 100 && note >= note0 && note < note_end; i++) { + if (!aligned(note, Elf32_Addr)) + return (FALSE); if (note->n_namesz != checknote->hdr.n_namesz || note->n_descsz != checknote->hdr.n_descsz || note->n_type != checknote->hdr.n_type)
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