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| author | Matthew Wilcox (Oracle) <willy@infradead.org> | 2020-01-17 17:45:12 -0500 |
|---|---|---|
| committer | Matthew Wilcox (Oracle) <willy@infradead.org> | 2020-01-17 22:32:24 -0500 |
| commit | 430f24f94c8a174d411a550d7b5529301922e67a (patch) | |
| tree | 7a23f31ee6f3bca6a09e1ce0c23fa62d4e65c5e1 | |
| parent | 82a958497dc9120e0e8043da82273baedd255aaf (diff) | |
| download | lwn-430f24f94c8a174d411a550d7b5529301922e67a.tar.gz lwn-430f24f94c8a174d411a550d7b5529301922e67a.zip | |
XArray: Fix infinite loop with entry at ULONG_MAX
If there is an entry at ULONG_MAX, xa_for_each() will overflow the
'index + 1' in xa_find_after() and wrap around to 0. Catch this case
and terminate the loop by returning NULL.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: stable@vger.kernel.org
| -rw-r--r-- | lib/test_xarray.c | 17 | ||||
| -rw-r--r-- | lib/xarray.c | 3 |
2 files changed, 20 insertions, 0 deletions
diff --git a/lib/test_xarray.c b/lib/test_xarray.c index c477f22a95cd..90584c63ca39 100644 --- a/lib/test_xarray.c +++ b/lib/test_xarray.c @@ -1046,11 +1046,28 @@ static noinline void check_find_3(struct xarray *xa) xa_destroy(xa); } +static noinline void check_find_4(struct xarray *xa) +{ + unsigned long index = 0; + void *entry; + + xa_store_index(xa, ULONG_MAX, GFP_KERNEL); + + entry = xa_find_after(xa, &index, ULONG_MAX, XA_PRESENT); + XA_BUG_ON(xa, entry != xa_mk_index(ULONG_MAX)); + + entry = xa_find_after(xa, &index, ULONG_MAX, XA_PRESENT); + XA_BUG_ON(xa, entry); + + xa_erase_index(xa, ULONG_MAX); +} + static noinline void check_find(struct xarray *xa) { check_find_1(xa); check_find_2(xa); check_find_3(xa); + check_find_4(xa); check_multi_find(xa); check_multi_find_2(xa); } diff --git a/lib/xarray.c b/lib/xarray.c index bfaaa2c1f3fe..6ecf35c2e1da 100644 --- a/lib/xarray.c +++ b/lib/xarray.c @@ -1849,6 +1849,9 @@ void *xa_find_after(struct xarray *xa, unsigned long *indexp, XA_STATE(xas, xa, *indexp + 1); void *entry; + if (xas.xa_index == 0) + return NULL; + rcu_read_lock(); for (;;) { if ((__force unsigned int)filter < XA_MAX_MARKS) |