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SubjectRe: [PATCH v2] kdb: Use strscpy with destination buffer size
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On 20/09/2018 13:59, Prarit Bhargava wrote:
> gcc 8.1.0 warns with:
>
> kernel/debug/kdb/kdb_support.c: In function ‘kallsyms_symbol_next’:
> kernel/debug/kdb/kdb_support.c:239:4: warning: ‘strncpy’ specified bound depends on the length of the source argument [-Wstringop-overflow=]
> strncpy(prefix_name, name, strlen(name)+1);
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> kernel/debug/kdb/kdb_support.c:239:31: note: length computed here
>
> Use strscpy() with the destination buffer size, and use ellipses when
> displaying truncated symbols.
>
> v2: Use strscpy()
>
> Signed-off-by: Prarit Bhargava <prarit@redhat.com>
> Cc: Jonathan Toppins <jtoppins@redhat.com>
> Cc: Jason Wessel <jason.wessel@windriver.com>
> Cc: Daniel Thompson <daniel.thompson@linaro.org>
> Cc: kgdb-bugreport@lists.sourceforge.net
> ---
> kernel/debug/kdb/kdb_io.c | 15 +++++++++------
> kernel/debug/kdb/kdb_private.h | 2 +-
> kernel/debug/kdb/kdb_support.c | 10 +++++-----
> 3 files changed, 15 insertions(+), 12 deletions(-)
>
> diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c
> index ed5d34925ad0..6a4b41484afe 100644
> --- a/kernel/debug/kdb/kdb_io.c
> +++ b/kernel/debug/kdb/kdb_io.c
> @@ -216,7 +216,7 @@ static char *kdb_read(char *buffer, size_t bufsize)
> int count;
> int i;
> int diag, dtab_count;
> - int key;
> + int key, buf_size, ret;
>
>
> diag = kdbgetintenv("DTABCOUNT", &dtab_count);
> @@ -336,9 +336,8 @@ static char *kdb_read(char *buffer, size_t bufsize)
> else
> p_tmp = tmpbuffer;
> len = strlen(p_tmp);
> - count = kallsyms_symbol_complete(p_tmp,
> - sizeof(tmpbuffer) -
> - (p_tmp - tmpbuffer));
> + buf_size = sizeof(tmpbuffer) - (p_tmp - tmpbuffer);
> + count = kallsyms_symbol_complete(p_tmp, buf_size);
> if (tab == 2 && count > 0) {
> kdb_printf("\n%d symbols are found.", count);
> if (count > dtab_count) {
> @@ -350,9 +349,13 @@ static char *kdb_read(char *buffer, size_t bufsize)
> }
> kdb_printf("\n");
> for (i = 0; i < count; i++) {
> - if (WARN_ON(!kallsyms_symbol_next(p_tmp, i)))
> + ret = kallsyms_symbol_next(p_tmp, i, buf_size);
> + if (WARN_ON(!ret))
> break;
I'm getting confused by having two different branches on ret.

Don't get a WARN_ON() when ret == -E2BIG?


Daniel.


> - kdb_printf("%s ", p_tmp);
> + if (ret != -E2BIG)
> + kdb_printf("%s ", p_tmp);
> + else
> + kdb_printf("%s... ", p_tmp);
> *(p_tmp + len) = '\0';
> }
> if (i >= dtab_count)

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