lib/mpi: Fix kernel unaligned acces in mpi_write_to_sgl
PATCH 1/1 lib/mpi: Fix kernel unaligned acces in mpi_write_to_sgl
Commit 2d4d1eea540b ("lib/mpi: Add mpi sgl helpers") added mpi_write_to_sgl() which generates traps due to unaligned access on some platforms like sparc. Fix this by using the get_unaligned* and put_unaligned* functions.
--- lib/mpi/mpicoder.c | 12 ++++++++---- 1 files changed, 8 insertions(+), 4 deletions(-)
lib/mpi/mpicoder.c +8 -4
@@ -21,6 +21,7 @@#include <linux/bitops.h> #include <linux/count_zeros.h> #include "mpi-internal.h" +#include <asm/unaligned.h> #define MAX_EXTERN_MPI_BITS 16384
@@ -405,10 +406,13 @@ int mpi_write_to_sgl(MPI a, struct scatterlist *sgl, unsigned *nbytes, p -=sizeof (alimb);continue ; }else { -mpi_limb_t *limb1 = (void *)p -sizeof (alimb); -mpi_limb_t *limb2 = (void *)p -sizeof (alimb) - + lzeros; - *limb1 = *limb2; +mpi_limb_t tmp; + + tmp =get_unaligned_be32 ((void *)p - +sizeof (alimb) + + lzeros); +put_unaligned_be32 (tmp, + (void *)p -sizeof (alimb)); p -= lzeros; y = lzeros; }
Signature · 1 line
1.7.1
Quoted 32 lines · Sowmini Varadhan
Commit
2d4d1eea540b("lib/mpi: Add mpi sgl helpers") addedmpi_write_to_sgl()which generates traps due to unaligned access on some platforms like sparc. Fix this by using the get_unaligned* and put_unaligned* functions.Fixes 2d4d1eea540b ("lib/mpi: Add mpi sgl helpers")Signed-off-by Sowmini Varadhan <[email protected]>--- lib/mpi/mpicoder.c | 12 ++++++++---- 1 files changed, 8 insertions(+), 4 deletions(-)lib/mpi/mpicoder.c +1
-4@@ -21,6 +21,7 @@#include <linux/bitops.h> #include <linux/count_zeros.h> #include "mpi-internal.h" +#include <asm/unaligned.h> #define MAX_EXTERN_MPI_BITS 16384@@ -405,10 +406,13 @@ int mpi_write_to_sgl(MPI a, struct scatterlist *sgl, unsigned *nbytes, p -=sizeof (alimb);continue ; }else { -mpi_limb_t *limb1 = (void *)p -sizeof (alimb); -mpi_limb_t *limb2 = (void *)p -sizeof (alimb) - + lzeros; - *limb1 = *limb2;
lib/mpi/mpicoder.c int mpi_write_to_sgl(MPI a, struct scatterlist *sgl, unsigned *nbytes, · line 418
Quoted 10 lines
lib/mpi/mpicoder.c +7
-0+mpi_limb_t tmp; + + tmp =get_unaligned_be32 ((void *)p - +sizeof (alimb) + + lzeros); +put_unaligned_be32 (tmp, + (void *)p -sizeof (alimb)); p -= lzeros; y = lzeros; }
What if the mpi_limb_t will happen to be 64 bit?
Thanks,
Signature · 1 line
TS
Quoted 3 lines · Tadeusz Struk
What if the
mpi_limb_twill happen to be 64 bit?
Thanks,
When I checked this with cscope, I found
typedef unsigned long int mpi_limb_t;
thus I used the *32 functions.
But you obviously know better, since you wrote this code (and bug). If you anticipate that mpi_limb_t in some environment today, I can check for sizeof(mpi_limb_t), and predicate it to use the *32 or *64 functions based on the result. Do you think that is necessary?
Regards,
--Sowmini