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| author | Josh Law <objecting@objecting.org> | 2026-03-18 10:48:05 +0300 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2026-03-28 07:19:48 +0300 |
| commit | f42b510990030bbc0d6e4ba4486decbcd952b924 (patch) | |
| tree | ecbf48fbb68b9a7f1dcff8a4d2cfc731cf5312ab | |
| parent | b8822d73d6fe0d43de3b98ccc995b7032993b1b7 (diff) | |
| download | linux-f42b510990030bbc0d6e4ba4486decbcd952b924.tar.xz | |
lib/bch: fix signed left-shift undefined behavior
Patch series "lib/bch: fix undefined behavior from signed left-shifts".
Fix two instances of undefined behavior in lib/bch.c caused by
left-shifting signed integers into or past the sign bit.
While the kernel's -fno-strict-overflow flag prevents miscompilation
today, these are formally UB per C11 6.5.7p4 and trivial to fix.
This patch (of 2):
Use 1u instead of 1 to avoid undefined behavior when left-shifting into
the sign bit of a signed int. deg() can return up to 31, and 1 << 31 is
UB per C11.
Link: https://lkml.kernel.org/r/20260318074806.16527-2-objecting@objecting.org
Signed-off-by: Josh Law <objecting@objecting.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Ivan Djelic <ivan.djelic@parrot.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | lib/bch.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/lib/bch.c b/lib/bch.c index 9561c0828802..ef733f08082f 100644 --- a/lib/bch.c +++ b/lib/bch.c @@ -392,7 +392,7 @@ static void compute_syndromes(struct bch_control *bch, uint32_t *ecc, for (j = 0; j < 2*t; j += 2) syn[j] ^= a_pow(bch, (j+1)*(i+s)); - poly ^= (1 << i); + poly ^= (1u << i); } } while (s > 0); @@ -612,7 +612,7 @@ static int find_poly_deg2_roots(struct bch_control *bch, struct gf_poly *poly, while (v) { i = deg(v); r ^= bch->xi_tab[i]; - v ^= (1 << i); + v ^= (1u << i); } /* verify root */ if ((gf_sqr(bch, r)^r) == u) { |