From d4d05d13eba6e0ed01767999fc87e75599ddd86e Mon Sep 17 00:00:00 2001 From: Alex Coplan Date: Mon, 17 Aug 2020 14:23:14 +0100 Subject: [PATCH] gas: Fix internal error in S_SET_SEGMENT This patch fixes an internal error in GAS when defining a section using a symbol that has already been named but not defined. For a minimal reproducer, try the following input: a=b .sect a The problem is that obj_elf_change_section() happily reuses the symbol "a" created by equals() without clearing the sy_value field: prior to this patch, it just set bsym. This caused a problem when attempting to resolve the section symbol, since resolve_symbol_value() ended up resolving the symbol as if it were the original symbol created by equals(), which ends up leaving the section symbol in the undefined section instead of in section a, hence the call to abort() in S_SET_SEGMENT(). gas/ChangeLog: * config/obj-elf.c (obj_elf_change_section): When repurposing an existing symbol, ensure that we set sy_value as per other (fresh) section symbols. * testsuite/gas/elf/elf.exp: Add new test. * testsuite/gas/elf/section-symbol-redef.d: New test. * testsuite/gas/elf/section-symbol-redef.s: Input for test. --- gas/ChangeLog | 9 +++++++++ gas/config/obj-elf.c | 9 ++++++++- gas/testsuite/gas/elf/elf.exp | 1 + gas/testsuite/gas/elf/section-symbol-redef.d | 5 +++++ gas/testsuite/gas/elf/section-symbol-redef.s | 3 +++ 5 files changed, 26 insertions(+), 1 deletion(-) create mode 100644 gas/testsuite/gas/elf/section-symbol-redef.d create mode 100644 gas/testsuite/gas/elf/section-symbol-redef.s diff --git a/gas/ChangeLog b/gas/ChangeLog index d9b57f8662..7c06ec9349 100644 --- a/gas/ChangeLog +++ b/gas/ChangeLog @@ -1,3 +1,12 @@ +2020-08-17 Alex Coplan + + * config/obj-elf.c (obj_elf_change_section): When repurposing an + existing symbol, ensure that we set sy_value as per other (fresh) + section symbols. + * testsuite/gas/elf/elf.exp: Add new test. + * testsuite/gas/elf/section-symbol-redef.d: New test. + * testsuite/gas/elf/section-symbol-redef.s: Input for test. + 2020-08-13 Nick Clifton PR 26359 diff --git a/gas/config/obj-elf.c b/gas/config/obj-elf.c index de22b5a1da..c11a1da229 100644 --- a/gas/config/obj-elf.c +++ b/gas/config/obj-elf.c @@ -759,7 +759,14 @@ obj_elf_change_section (const char *name, /* Add a symbol for this section to the symbol table. */ secsym = symbol_find (name); if (secsym != NULL) - symbol_set_bfdsym (secsym, sec->symbol); + { + /* We could be repurposing an undefined symbol here: make sure we + reset sy_value to look like other section symbols in order to avoid + trying to incorrectly resolve this section symbol later on. */ + static const expressionS expr = { .X_op = O_constant }; + symbol_set_value_expression (secsym, &expr); + symbol_set_bfdsym (secsym, sec->symbol); + } else symbol_table_insert (section_symbol (sec)); } diff --git a/gas/testsuite/gas/elf/elf.exp b/gas/testsuite/gas/elf/elf.exp index 155f78efa7..2f9893b3d2 100644 --- a/gas/testsuite/gas/elf/elf.exp +++ b/gas/testsuite/gas/elf/elf.exp @@ -305,6 +305,7 @@ if { [is_elf_format] } then { run_dump_test "strtab" run_dump_test "bignums" + run_dump_test "section-symbol-redef" load_lib gas-dg.exp dg-init diff --git a/gas/testsuite/gas/elf/section-symbol-redef.d b/gas/testsuite/gas/elf/section-symbol-redef.d new file mode 100644 index 0000000000..2ce245246f --- /dev/null +++ b/gas/testsuite/gas/elf/section-symbol-redef.d @@ -0,0 +1,5 @@ +#readelf: -x myseg +#notarget: bfin-*-* h8300-* + +Hex dump of section .*: + 0x0+ 2a\s+\* diff --git a/gas/testsuite/gas/elf/section-symbol-redef.s b/gas/testsuite/gas/elf/section-symbol-redef.s new file mode 100644 index 0000000000..87e65699b4 --- /dev/null +++ b/gas/testsuite/gas/elf/section-symbol-redef.s @@ -0,0 +1,3 @@ + myseg=not_defined_here + .section myseg + .byte 42 -- 2.34.1