From: Eric Biggers <ebiggers@kernel.org> stable inclusion from stable-v6.6.135 commit 066c760acead1fb743bae294dbd89f479ae43b9b category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/14894 CVE: CVE-2026-43336 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit e5046823f8fa3677341b541a25af2fcb99a5b1e0 upstream. Since the ChaCha permutation is invertible, the local variable 'permuted_state' is sufficient to compute the original 'state', and thus the key, even after the permutation has been done. While the kernel is quite inconsistent about zeroizing secrets on the stack (and some prominent userspace crypto libraries don't bother at all since it's not guaranteed to work anyway), the kernel does try to do it as a best practice, especially in cases involving the RNG. Thus, explicitly zeroize 'permuted_state' before it goes out of scope. Fixes: c08d0e647305 ("crypto: chacha20 - Add a generic ChaCha20 stream cipher implementation") Cc: stable@vger.kernel.org Acked-by: Ard Biesheuvel <ardb@kernel.org> Link: https://lore.kernel.org/r/20260326032920.39408-1-ebiggers@kernel.org Signed-off-by: Eric Biggers <ebiggers@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Yi Yang <yiyang13@huawei.com> --- lib/crypto/chacha.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/lib/crypto/chacha.c b/lib/crypto/chacha.c index b748fd3d256e..1bff9f283777 100644 --- a/lib/crypto/chacha.c +++ b/lib/crypto/chacha.c @@ -86,6 +86,8 @@ void chacha_block_generic(u32 *state, u8 *stream, int nrounds) put_unaligned_le32(x[i] + state[i], &stream[i * sizeof(u32)]); state[12]++; + + memzero_explicit(x, sizeof(x)); } EXPORT_SYMBOL(chacha_block_generic); @@ -110,5 +112,7 @@ void hchacha_block_generic(const u32 *state, u32 *stream, int nrounds) memcpy(&stream[0], &x[0], 16); memcpy(&stream[4], &x[12], 16); + + memzero_explicit(x, sizeof(x)); } EXPORT_SYMBOL(hchacha_block_generic); -- 2.25.1