gdb: fix nullptr dereference in block::ranges()
This commit:
commit f5cb8afdd297dd68273d98a10fbfd350dff918d8
Date: Sun Feb 6 22:27:53 2022 -0500
gdb: remove BLOCK_RANGES macro
introduces a potential nullptr dereference in block::ranges, this is
breaking most tests, e.g. gdb.base/break.exp is failing for me.
In the above patch BLOCK_CONTIGUOUS_P is changed from this:
#define BLOCK_CONTIGUOUS_P(bl) (BLOCK_RANGES (bl) == nullptr \
|| BLOCK_NRANGES (bl) <= 1)
to this:
#define BLOCK_CONTIGUOUS_P(bl) ((bl)->ranges ().size () == 0 \
|| (bl)->ranges ().size () == 1)
So, before the commit we checked for the block ranges being nullptr,
but afterwards we just call block::ranges() in all cases.
The problem is that block::ranges() looks like this:
/* Return a view on this block's ranges. */
gdb::array_view<blockrange> ranges ()
{ return gdb::make_array_view (m_ranges->range, m_ranges->nranges); }
where m_ranges is:
struct blockranges *m_ranges;
And so, we see that the nullptr check has been lost, and we might end
up dereferencing a nullptr.
My proposed fix is to move the nullptr check into block::ranges, and
return an explicit empty array_view if m_ranges is nullptr.
After this, everything seems fine again.
1 file changed
