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842 struct aesni_xts_ctx *ctx = crypto_skcipher_ctx(tfm); 843 int tail = req->cryptlen % AES_BLOCK_SIZE; 844 struct skcipher_request subreq; 845 struct skcipher_walk walk; 846 int err; 847 848 if (req->cryptlen < AES_BLOCK_SIZE) 849 return -EINVAL; 850 851 err = skcipher_walk_virt(&walk, req, false); 852 if (!walk.nbytes) 853 return err; The patch adds this check for "walk.nbytes == 0". 854 855 if (unlikely(tail > 0 && walk.nbytes < walk.total)) { ^^^^^^^^^^^^^^^^^^^^^^^^ But Smatch says that "walk.nbytes" can be set to zero inside this if statement. 856 int blocks = DIV_ROUND_UP(req->cryptlen, AES_BLOCK_SIZE) - 2; 857 858 skcipher_walk_abort(&walk); 859 860 skcipher_request_set_tfm(&subreq, tfm); 861 skcipher_request_set_callback(&subreq, 862 skcipher_request_flags(req), 863 NULL, NULL); 864 skcipher_request_set_crypt(&subreq, req->src, req->dst, 865 blocks * AES_BLOCK_SIZE, req->iv); 866 req = &subreq; 867 868 err = skcipher_walk_virt(&walk, req, false); 869 if (err) 870 return err; 871 } else { 872 tail = 0; 873 } 874 875 kernel_fpu_begin(); 876 877 /* calculate first value of T */ 878 aesni_enc(aes_ctx(ctx->raw_tweak_ctx), walk.iv, walk.iv); 879 Leading to not entering this loop and so we don't restore kernel_fpu_end(). So maybe the "if (walk.nbytes == 0)" check should be moved to right before the call to kernel_fpu_begin()? 880 while (walk.nbytes > 0) { 881 int nbytes = walk.nbytes; 882 883 if (nbytes < walk.total) 884 nbytes &= ~(AES_BLOCK_SIZE - 1); 885 886 if (encrypt) 887 aesni_xts_encrypt(aes_ctx(ctx->raw_crypt_ctx), 888 walk.dst.virt.addr, walk.src.virt.addr, 889 nbytes, walk.iv); 890 else 891 aesni_xts_decrypt(aes_ctx(ctx->raw_crypt_ctx), 892 walk.dst.virt.addr, walk.src.virt.addr, 893 nbytes, walk.iv); 894 kernel_fpu_end(); 895 896 err = skcipher_walk_done(&walk, walk.nbytes - nbytes); 897 898 if (walk.nbytes > 0) 899 kernel_fpu_begin(); 900 } 901 902 if (unlikely(tail > 0 && !err)) { 903 struct scatterlist sg_src[2], sg_dst[2]; 904 struct scatterlist *src, *dst; 905 906 dst = src = scatterwalk_ffwd(sg_src, req->src, req->cryptlen); 907 if (req->dst != req->src) 908 dst = scatterwalk_ffwd(sg_dst, req->dst, req->cryptlen); 909 910 skcipher_request_set_crypt(req, src, dst, AES_BLOCK_SIZE + tail, 911 req->iv); 912 913 err = skcipher_walk_virt(&walk, &subreq, false); 914 if (err) --> 915 return err; 916 917 kernel_fpu_begin(); 918 if (encrypt) 919 aesni_xts_encrypt(aes_ctx(ctx->raw_crypt_ctx), 920 walk.dst.virt.addr, walk.src.virt.addr, 921 walk.nbytes, walk.iv); 922 else 923 aesni_xts_decrypt(aes_ctx(ctx->raw_crypt_ctx), 924 walk.dst.virt.addr, walk.src.virt.addr, 925 walk.nbytes, walk.iv); 926 kernel_fpu_end(); 927 928 err = skcipher_walk_done(&walk, 0); 929 } 930 return err; 931 } regards, dan carpenter