Messages in this thread Patch in this message | | | From | Ayush Mittal <> | Subject | [PATCH 1/1] mpi: check for shift exponent greater than 31. | Date | Tue, 24 Oct 2017 10:57:03 +0530 |
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This patch check for shift exponent greater than 31, detected by UBSAN.
1)UBSAN: Undefined behaviour in lib/mpi/generic_mpih-lshift.c:57:22 shift exponent 32 is too large for 32-bit type 'long unsigned int'
2)UBSAN: Undefined behaviour in lib/mpi/generic_mpih-lshift.c:60:20 shift exponent 32 is too large for 32-bit type 'long unsigned int'
3)UBSAN: Undefined behaviour in lib/mpi/generic_mpih-rshift.c:57:21 shift exponent 32 is too large for 32-bit type 'long unsigned int'
4) UBSAN: Undefined behaviour in lib/mpi/generic_mpih-rshift.c:60:19 shift exponent 32 is too large for 32-bit type 'long unsigned int'
So instead of undefined behaviour defining behaviour when shift exponent is greater than 31 then value will be Zero .
Signed-off-by: Ayush Mittal <ayush.m@samsung.com> Signed-off-by: Vaneet Narang <v.narang@samsung.com> --- lib/mpi/generic_mpih-lshift.c | 6 +++--- lib/mpi/generic_mpih-rshift.c | 6 +++--- lib/mpi/mpi-internal.h | 3 +++ 3 files changed, 9 insertions(+), 6 deletions(-)
diff --git a/lib/mpi/generic_mpih-lshift.c b/lib/mpi/generic_mpih-lshift.c index 8631892..1c8277e 100644 --- a/lib/mpi/generic_mpih-lshift.c +++ b/lib/mpi/generic_mpih-lshift.c @@ -50,14 +50,14 @@ sh_2 = BITS_PER_MPI_LIMB - sh_1; i = usize - 1; low_limb = up[i]; - retval = low_limb >> sh_2; + retval = MPI_RSHIFT(low_limb, sh_2); high_limb = low_limb; while (--i >= 0) { low_limb = up[i]; - wp[i] = (high_limb << sh_1) | (low_limb >> sh_2); + wp[i] = MPI_LSHIFT(high_limb, sh_1) | MPI_RSHIFT(low_limb, sh_2); high_limb = low_limb; } - wp[i] = high_limb << sh_1; + wp[i] = MPI_LSHIFT(high_limb, sh_1); return retval; } diff --git a/lib/mpi/generic_mpih-rshift.c b/lib/mpi/generic_mpih-rshift.c index ffa3288..3a28bdd 100644 --- a/lib/mpi/generic_mpih-rshift.c +++ b/lib/mpi/generic_mpih-rshift.c @@ -50,14 +50,14 @@ wp -= 1; sh_2 = BITS_PER_MPI_LIMB - sh_1; high_limb = up[0]; - retval = high_limb << sh_2; + retval = MPI_LSHIFT(high_limb, sh_2); low_limb = high_limb; for (i = 1; i < usize; i++) { high_limb = up[i]; - wp[i] = (low_limb >> sh_1) | (high_limb << sh_2); + wp[i] = MPI_RSHIFT(low_limb, sh_1) | MPI_LSHIFT(high_limb, sh_2); low_limb = high_limb; } - wp[i] = low_limb >> sh_1; + wp[i] = MPI_RSHIFT(low_limb, sh_1); return retval; } diff --git a/lib/mpi/mpi-internal.h b/lib/mpi/mpi-internal.h index 7eceedd..9c94a98 100644 --- a/lib/mpi/mpi-internal.h +++ b/lib/mpi/mpi-internal.h @@ -37,6 +37,9 @@ #include <linux/mpi.h> #include <linux/errno.h> +#define MPI_LSHIFT(val, shift) (shift >= BITS_PER_MPI_LIMB ? 0 : (val << shift)) +#define MPI_RSHIFT(val, shift) (shift >= BITS_PER_MPI_LIMB ? 0 : (val >> shift)) + #define log_debug printk #define log_bug printk -- 1.9.1
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