Commit b07829d5 authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Petr Mladek
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vsnprintf: drop __printf() attributes on binary printing functions 

The printf() format attributes are applied inconsistently for the binary
printf helpers, which causes warnings for the bpf_trace code using
them from functions that pass down format strings:

    kernel/trace/bpf_trace.c: In function '____bpf_trace_printk':
    kernel/trace/bpf_trace.c:377:9: error: function '____bpf_trace_printk' might be a candidate for 'gnu_printf' format attribute [-Werror=suggest-attribute=format]
      377 |         ret = bstr_printf(data.buf, MAX_BPRINTF_BUF, fmt, data.bin_args);
          |         ^~~

This can be addressed either by annotating all five callers in bpf code,
or by removing the annotations on the callees that were added by Andy
Shevchenko last year.

As Alexei Starovoitov points out, there are no callers in C code that
would benefit from the __printf attributes, the only users are in BPF
code or in the do_trace_printk() helper that already checks the arguments.

Drop all three of these annotations, reverting the earlierl commits that
added these, in order to get a clean build with -Wsuggest-attribute=format.

Fixes: 6b2c1e30 ("seq_file: Mark binary printing functions with __printf() attribute")
Fixes: 7bf819aa ("vsnprintf: Mark binary printing functions with __printf() attribute")
Link: https://lore.kernel.org/all/CAADnVQK3eZp3yp35OUx8j1UBsQFhgsn5-4VReqAJ=68PaaKYmg@mail.gmail.com/


Reported-by: default avatarkernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202512061640.9hKTnB8p-lkp@intel.com/


Suggested-by: default avatarAlexei Starovoitov <alexei.starovoitov@gmail.com>
Acked-by: default avatarAlexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
Acked-by: default avatarPetr Mladek <pmladek@suse.com>
Acked-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patch.msgid.link/20260204132643.1302967-1-arnd@kernel.org


Signed-off-by: default avatarPetr Mladek <pmladek@suse.com>
parent 9bfa52da

include/linux/seq_file.h

+0 −1
Original line number Diff line number Diff line
@@ -181,7 +181,6 @@ int seq_open_private(struct file *, const struct seq_operations *, int); 
int seq_release_private(struct inode *, struct file *);



#ifdef CONFIG_BINARY_PRINTF

__printf(2, 0)

void seq_bprintf(struct seq_file *m, const char *f, const u32 *binary);

#endif

include/linux/string.h

+2 −2
Original line number Diff line number Diff line
@@ -336,8 +336,8 @@ int __sysfs_match_string(const char * const *array, size_t n, const char *s); 
#define sysfs_match_string(_a, _s) __sysfs_match_string(_a, ARRAY_SIZE(_a), _s)



#ifdef CONFIG_BINARY_PRINTF

__printf(3, 0) int vbin_printf(u32 *bin_buf, size_t size, const char *fmt, va_list args);

__printf(3, 0) int bstr_printf(char *buf, size_t size, const char *fmt, const u32 *bin_buf);

int vbin_printf(u32 *bin_buf, size_t size, const char *fmt, va_list args);

int bstr_printf(char *buf, size_t size, const char *fmt, const u32 *bin_buf);

#endif



extern ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,