| Message ID | 4DA4B68B.9000907@seznam.cz (mailing list archive) |
|---|---|
| State | Rejected, archived |
| Headers | show |
diff --git a/linearize.c b/linearize.c index f2034ce..e29ebe8 100644 --- a/linearize.c +++ b/linearize.c @@ -313,6 +313,10 @@ const char *show_instruction(struct instruction *insn) struct symbol *sym = insn->symbol->sym; buf += sprintf(buf, "%s <- ", show_pseudo(insn->target)); + if (!sym) { + buf += sprintf(buf, "<missing_symbol>"); + break; + } if (sym->bb_target) { buf += sprintf(buf, ".L%p", sym->bb_target); break;
The corner case addressed by this patch can be triggered, e.g., with this command (`sparse' can be substituted with `test-linearize' in which case `-ventry' is not required): $ ./sparse -vv -ventry compat/mmap-blob.c compat/mmap-blob.c:20:21: error: undefined identifier 'CHUNK' compat/mmap-blob.c:21:17: error: undefined identifier 'die' compat/mmap-blob.c:22:20: error: undefined identifier 'NULL' compat/mmap-blob.c:24:23: error: undefined identifier 'NULL' compat/mmap-blob.c:30:31: error: undefined identifier 'CHUNK' compat/mmap-blob.c:31:17: error: undefined identifier 'die' blob_alloc: ep 0xb74f700c: blob_alloc .L0xb74ef00c: compat/mmap-blob.c:16 <entry-point> # snop.32 VOID -> 0[size] # lnop.32 %r1 <- 0[size] Segmentation fault The problem here is that no semantical meaning is found for `CHUNK' identifier (sparse emits an error for this properly) so the respective symbol is stored as a "missing" (NULL) reference in the resulting semantical tree, connected with OP_SYMADDR instruction. With described example, we would normally never have encountered this as the problematic instruction is inactive -- unless we use "be double-verbose" (-vv) switch. This makes sparse library output also such inactive instructions, and when it comes to our OP_SYMADDR, it does segfault due to NULL pointer dereference. The underscore convention mimics the usage of other angle-bracketed labels (namely "<bad_string>" in tokenize.c). Signed-off-by: Jan Pokorny <pokorny_jan@seznam.cz> --- linearize.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-)