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authorJosh Poimboeuf <jpoimboe@redhat.com>2020-04-25 14:19:01 -0500
committerIngo Molnar <mingo@kernel.org>2020-04-26 09:28:14 +0200
commit53fb6e990d782ded62d7c76d566e107c03393b74 (patch)
tree1943d71dada4b2ad2c49fbc8a2c43c7ccd142fe6 /tools
parent81b67439d147677d844d492fcbd03712ea438f42 (diff)
objtool: Fix infinite loop in for_offset_range()
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: 74b873e49d92 ("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
Diffstat (limited to 'tools')
-rw-r--r--tools/objtool/elf.h7
1 files changed, 4 insertions, 3 deletions
diff --git a/tools/objtool/elf.h b/tools/objtool/elf.h
index ebbb10c61e24..c227a2e55751 100644
--- a/tools/objtool/elf.h
+++ b/tools/objtool/elf.h
@@ -87,9 +87,10 @@ struct elf {
#define OFFSET_STRIDE (1UL << OFFSET_STRIDE_BITS)
#define OFFSET_STRIDE_MASK (~(OFFSET_STRIDE - 1))
-#define for_offset_range(_offset, _start, _end) \
- for (_offset = ((_start) & OFFSET_STRIDE_MASK); \
- _offset <= ((_end) & OFFSET_STRIDE_MASK); \
+#define for_offset_range(_offset, _start, _end) \
+ for (_offset = ((_start) & OFFSET_STRIDE_MASK); \
+ _offset >= ((_start) & OFFSET_STRIDE_MASK) && \
+ _offset <= ((_end) & OFFSET_STRIDE_MASK); \
_offset += OFFSET_STRIDE)
static inline u32 sec_offset_hash(struct section *sec, unsigned long offset)