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ss: fix crash when skipping disabled header field 

When the first header field is disabled (i.e. when passing the -t
option), field_flush() is invoked with the `buffer` global variable
still zero'd.
However, in field_flush() we try to access buffer.cur->len
during variables initialization, thus leading to a SIGSEGV.

It's interesting to note that this bug appears only when the code
is compiled with -O0, because the compiler is smart
enough to immediately jump to the return statement if optimizations
are enabled and skip the faulty instruction.

Cc: Stefano Brivio <sbrivio@redhat.com>
Cc: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Antonio Quartulli <a@unstable.cc>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
This commit is contained in:
Antonio Quartulli 2018-01-07 02:31:49 +08:00 committed by Stephen Hemminger
parent 33f6dd23a5
commit 192be8fccb
1 changed files with 5 additions and 2 deletions
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7
misc/ss.c
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@ -1018,12 +1018,15 @@ static void print_right_spacing(struct column *f, int printed)
/* Done with field: update buffer pointer, start new token after current one */ /* Done with field: update buffer pointer, start new token after current one */
static void field_flush(struct column *f) static void field_flush(struct column *f)
{ {
struct buf_chunk *chunk = buffer.tail; struct buf_chunk *chunk;
unsigned int pad = buffer.cur->len % 2; unsigned int pad;
if (f->disabled) if (f->disabled)
return; return;
chunk = buffer.tail;
pad = buffer.cur->len % 2;
if (buffer.cur->len > f->max_len) if (buffer.cur->len > f->max_len)
f->max_len = buffer.cur->len; f->max_len = buffer.cur->len;