[PATCH AUTOSEL 5.4 23/26] recordmcount: Correct st_shndx handling

Sasha Levin
2021-06-21T18:00:56Z

From: Peter Zijlstra <peterz@infradead.org>

[ Upstream commit fb780761e7bd9f2e94f5b9a296ead6b35b944206 ]

One should only use st_shndx when >SHN_UNDEF and <SHN_LORESERVE. When
SHN_XINDEX, then use .symtab_shndx. Otherwise use 0.

This handles the case: st_shndx >= SHN_LORESERVE && st_shndx != SHN_XINDEX.

Link: https://lore.kernel.org/lkml/20210607023839.26387-1-mark-pk.tsai@mediatek.com/
Link: https://lkml.kernel.org/r/20210616154126.2794-1-mark-pk.tsai@mediatek.com

Reported-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
Tested-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
[handle endianness of sym->st_shndx]
Signed-off-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
scripts/recordmcount.h | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/scripts/recordmcount.h b/scripts/recordmcount.h
index f9b19524da11..1e9baa5c4fc6 100644
--- a/scripts/recordmcount.h
+++ b/scripts/recordmcount.h
@@ -192,15 +192,20 @@ static unsigned int get_symindex(Elf_Sym const *sym, Elf32_Word const *symtab,
Elf32_Word const *symtab_shndx)
{
unsigned long offset;
+ unsigned short shndx = w2(sym->st_shndx);
int index;

- if (sym->st_shndx != SHN_XINDEX)
- return w2(sym->st_shndx);
+ if (shndx > SHN_UNDEF && shndx < SHN_LORESERVE)
+ return shndx;

- offset = (unsigned long)sym - (unsigned long)symtab;
- index = offset / sizeof(*sym);
+ if (shndx == SHN_XINDEX) {
+ offset = (unsigned long)sym - (unsigned long)symtab;
+ index = offset / sizeof(*sym);

- return w(symtab_shndx[index]);
+ return w(symtab_shndx[index]);
+ }
+
+ return 0;
}

static unsigned int get_shnum(Elf_Ehdr const *ehdr, Elf_Shdr const *shdr0)
--
2.30.2