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XArray: Fix xas_create_range for ranges above 4 billion 

The 'sibs' variable would be shifted as a 32-bit integer, so if 'shift'
is more than 32, this is undefined behaviour.  In practice, this doesn't
happen because the page cache is the only user and nobody uses 16TB pages.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
zero-sugar-mainline-defconfig
Matthew Wilcox (Oracle) 2020-10-13 08:46:29 -04:00
parent f78b8250a0
commit 84c34df158
1 changed files with 1 additions and 1 deletions
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lib/xarray.c
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@ -703,7 +703,7 @@ void xas_create_range(struct xa_state *xas)
unsigned char shift = xas->xa_shift;
unsigned char sibs = xas->xa_sibs;
xas->xa_index |= ((sibs + 1) << shift) - 1;
xas->xa_index |= ((sibs + 1UL) << shift) - 1;
if (xas_is_node(xas) && xas->xa_node->shift == xas->xa_shift)
xas->xa_offset |= sibs;
xas->xa_shift = 0;