53fb6e990d
Randy reported that objtool got stuck in an infinite loop when
processing drivers/i2c/busses/i2c-parport.o. It was caused by the
following code:
00000000000001fd <line_set>:
1fd: 48 b8 00 00 00 00 00 movabs $0x0,%rax
204: 00 00 00
1ff: R_X86_64_64 .rodata-0x8
207: 41 55 push %r13
209: 41 89 f5 mov %esi,%r13d
20c: 41 54 push %r12
20e: 49 89 fc mov %rdi,%r12
211: 55 push %rbp
212: 48 89 d5 mov %rdx,%rbp
215: 53 push %rbx
216: 0f b6 5a 01 movzbl 0x1(%rdx),%ebx
21a: 48 8d 34 dd 00 00 00 lea 0x0(,%rbx,8),%rsi
221: 00
21e: R_X86_64_32S .rodata
222: 48 89 f1 mov %rsi,%rcx
225: 48 29 c1 sub %rax,%rcx
find_jump_table() saw the .rodata reference and tried to find a jump
table associated with it (though there wasn't one). The -0x8 rela
addend is unusual. It caused find_jump_table() to send a negative
table_offset (unsigned 0xfffffffffffffff8) to find_rela_by_dest().
The negative offset should have been harmless, but it actually threw
for_offset_range() for a loop... literally. When the mask value got
incremented past the end value, it also wrapped to zero, causing the
loop exit condition to remain true forever.
Prevent this scenario from happening by ensuring the incremented value
is always >= the starting value.
Fixes: 74b873e49d ("objtool: Optimize find_rela_by_dest_range()")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Julien Thierry <jthierry@redhat.com>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/02b719674b031800b61e33c30b2e823183627c19.1587842122.git.jpoimboe@redhat.com
136 lines
3.5 KiB
C
136 lines
3.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* Copyright (C) 2015 Josh Poimboeuf <jpoimboe@redhat.com>
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*/
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#ifndef _OBJTOOL_ELF_H
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#define _OBJTOOL_ELF_H
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#include <stdio.h>
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#include <gelf.h>
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#include <linux/list.h>
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#include <linux/hashtable.h>
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#include <linux/rbtree.h>
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#include <linux/jhash.h>
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#ifdef LIBELF_USE_DEPRECATED
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# define elf_getshdrnum elf_getshnum
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# define elf_getshdrstrndx elf_getshstrndx
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#endif
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/*
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* Fallback for systems without this "read, mmaping if possible" cmd.
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*/
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#ifndef ELF_C_READ_MMAP
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#define ELF_C_READ_MMAP ELF_C_READ
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#endif
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struct section {
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struct list_head list;
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struct hlist_node hash;
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struct hlist_node name_hash;
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GElf_Shdr sh;
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struct rb_root symbol_tree;
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struct list_head symbol_list;
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struct list_head rela_list;
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struct section *base, *rela;
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struct symbol *sym;
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Elf_Data *data;
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char *name;
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int idx;
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unsigned int len;
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bool changed, text, rodata;
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};
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struct symbol {
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struct list_head list;
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struct rb_node node;
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struct hlist_node hash;
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struct hlist_node name_hash;
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GElf_Sym sym;
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struct section *sec;
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char *name;
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unsigned int idx;
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unsigned char bind, type;
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unsigned long offset;
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unsigned int len;
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struct symbol *pfunc, *cfunc, *alias;
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bool uaccess_safe;
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};
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struct rela {
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struct list_head list;
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struct hlist_node hash;
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GElf_Rela rela;
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struct section *sec;
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struct symbol *sym;
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unsigned int type;
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unsigned long offset;
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int addend;
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bool jump_table_start;
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};
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struct elf {
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Elf *elf;
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GElf_Ehdr ehdr;
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int fd;
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char *name;
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struct list_head sections;
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DECLARE_HASHTABLE(symbol_hash, 20);
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DECLARE_HASHTABLE(symbol_name_hash, 20);
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DECLARE_HASHTABLE(section_hash, 16);
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DECLARE_HASHTABLE(section_name_hash, 16);
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DECLARE_HASHTABLE(rela_hash, 20);
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};
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#define OFFSET_STRIDE_BITS 4
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#define OFFSET_STRIDE (1UL << OFFSET_STRIDE_BITS)
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#define OFFSET_STRIDE_MASK (~(OFFSET_STRIDE - 1))
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#define for_offset_range(_offset, _start, _end) \
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for (_offset = ((_start) & OFFSET_STRIDE_MASK); \
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_offset >= ((_start) & OFFSET_STRIDE_MASK) && \
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_offset <= ((_end) & OFFSET_STRIDE_MASK); \
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_offset += OFFSET_STRIDE)
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static inline u32 sec_offset_hash(struct section *sec, unsigned long offset)
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{
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u32 ol, oh, idx = sec->idx;
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offset &= OFFSET_STRIDE_MASK;
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ol = offset;
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oh = offset >> 32;
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__jhash_mix(ol, oh, idx);
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return ol;
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}
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static inline u32 rela_hash(struct rela *rela)
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{
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return sec_offset_hash(rela->sec, rela->offset);
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}
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struct elf *elf_read(const char *name, int flags);
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struct section *find_section_by_name(struct elf *elf, const char *name);
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struct symbol *find_func_by_offset(struct section *sec, unsigned long offset);
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struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset);
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struct symbol *find_symbol_by_name(struct elf *elf, const char *name);
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struct symbol *find_symbol_containing(struct section *sec, unsigned long offset);
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struct rela *find_rela_by_dest(struct elf *elf, struct section *sec, unsigned long offset);
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struct rela *find_rela_by_dest_range(struct elf *elf, struct section *sec,
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unsigned long offset, unsigned int len);
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struct symbol *find_func_containing(struct section *sec, unsigned long offset);
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struct section *elf_create_section(struct elf *elf, const char *name, size_t
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entsize, int nr);
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struct section *elf_create_rela_section(struct elf *elf, struct section *base);
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int elf_rebuild_rela_section(struct section *sec);
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int elf_write(struct elf *elf);
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void elf_close(struct elf *elf);
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#define for_each_sec(file, sec) \
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list_for_each_entry(sec, &file->elf->sections, list)
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#endif /* _OBJTOOL_ELF_H */
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