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objtool: Fix truncated string warning

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On GCC 12, the build fails due to a possible truncated string:

    check.c: In function 'validate_call':
    check.c:2865:58: error: '%d' directive output may be truncated writing between 1 and 10 bytes into a region of size 9 [-Werror=format-truncation=]
     2865 |                 snprintf(pvname, sizeof(pvname), "pv_ops[%d]", idx);
          |                                                          ^~

In theory it's a valid bug:

    static char pvname[16];
    int idx;
    ...
    idx = (rel->addend / sizeof(void *));
    snprintf(pvname, sizeof(pvname), "pv_ops[%d]", idx);

There are only 7 chars for %d while it could take up to 9, so the
printed "pv_ops[%d]" string could get truncated.

In reality the bug should never happen, because pv_ops only has ~80
entries, so 7 chars for the integer is more than enough.  Still, it's
worth fixing.  Bump the buffer size by 2 bytes to silence the warning.

[ jpoimboe: changed size to 19; massaged changelog ]

Fixes: db2b0c5d7b ("objtool: Support pv_opsindirect calls for noinstr")
Reported-by: Adam Borowski <kilobyte@angband.pl>
Reported-by: Martin Liška <mliska@suse.cz>
Signed-off-by: Sergei Trofimovich <slyich@gmail.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220120233748.2062559-1-slyich@gmail.com
This commit is contained in:
Sergei Trofimovich 2022-01-20 23:37:48 +00:00 committed by Josh Poimboeuf
parent e783362eb5
commit 82880283d7
1 changed files with 1 additions and 1 deletions
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2
tools/objtool/check.c
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@ -2854,7 +2854,7 @@ static inline bool func_uaccess_safe(struct symbol *func)
static inline const char *call_dest_name(struct instruction *insn)
{
static char pvname[16];
static char pvname[19];
struct reloc *rel;
int idx;