| Message ID | 20210918111805.15471-1-len.baker@gmx.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | scsi: advansys: Prefer struct_size over open coded arithmetic | expand |
On 9/18/21 06:18, Len Baker wrote: > As noted in the "Deprecated Interfaces, Language Features, Attributes, > and Conventions" documentation [1], size calculations (especially > multiplication) should not be performed in memory allocator (or similar) > function arguments due to the risk of them overflowing. This could lead > to values wrapping around and a smaller allocation being made than the > caller was expecting. Using those allocations could lead to linear > overflows of heap memory and other misbehaviors. > > So, refactor the code a bit to use the struct_size() helper instead of > the argument "size + count * size" in the kzalloc() function. > > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments > > Signed-off-by: Len Baker <len.baker@gmx.com> > --- > drivers/scsi/advansys.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/scsi/advansys.c b/drivers/scsi/advansys.c > index ffb391967573..fe882502e7bf 100644 > --- a/drivers/scsi/advansys.c > +++ b/drivers/scsi/advansys.c > @@ -7465,6 +7465,7 @@ static int asc_build_req(struct asc_board *boardp, struct scsi_cmnd *scp, > return ASC_BUSY; > } else if (use_sg > 0) { > int sgcnt; > + size_t size; I don't think a new variable is needed. > struct scatterlist *slp; > struct asc_sg_head *asc_sg_head; > > @@ -7477,8 +7478,8 @@ static int asc_build_req(struct asc_board *boardp, struct scsi_cmnd *scp, > return ASC_ERROR; > } > > - asc_sg_head = kzalloc(sizeof(asc_scsi_q->sg_head) + > - use_sg * sizeof(struct asc_sg_list), GFP_ATOMIC); > + size = struct_size(asc_scsi_q->sg_head, sg_list, use_sg); > + asc_sg_head = kzalloc(size, GFP_ATOMIC); You can go with this: diff --git a/drivers/scsi/advansys.c b/drivers/scsi/advansys.c index ffb391967573..e341b3372482 100644 --- a/drivers/scsi/advansys.c +++ b/drivers/scsi/advansys.c @@ -7477,8 +7477,8 @@ static int asc_build_req(struct asc_board *boardp, struct scsi_cmnd *scp, return ASC_ERROR; } - asc_sg_head = kzalloc(sizeof(asc_scsi_q->sg_head) + - use_sg * sizeof(struct asc_sg_list), GFP_ATOMIC); + asc_sg_head = kzalloc(struct_size(asc_sg_head, sg_list, use_sg), + GFP_ATOMIC); if (!asc_sg_head) { scsi_dma_unmap(scp); set_host_byte(scp, DID_SOFT_ERROR); It perfectly fits withing the 80 columns, which by the way is deprecated but still good-to-have. Also, if you are finding these instances with the help of Coccinelle, it'd be nice if you mention that in the changelog text. :) Thanks! -- Gustavo > if (!asc_sg_head) { > scsi_dma_unmap(scp); > set_host_byte(scp, DID_SOFT_ERROR); > -- > 2.25.1 >
diff --git a/drivers/scsi/advansys.c b/drivers/scsi/advansys.c index ffb391967573..fe882502e7bf 100644 --- a/drivers/scsi/advansys.c +++ b/drivers/scsi/advansys.c @@ -7465,6 +7465,7 @@ static int asc_build_req(struct asc_board *boardp, struct scsi_cmnd *scp, return ASC_BUSY; } else if (use_sg > 0) { int sgcnt; + size_t size; struct scatterlist *slp; struct asc_sg_head *asc_sg_head; @@ -7477,8 +7478,8 @@ static int asc_build_req(struct asc_board *boardp, struct scsi_cmnd *scp, return ASC_ERROR; } - asc_sg_head = kzalloc(sizeof(asc_scsi_q->sg_head) + - use_sg * sizeof(struct asc_sg_list), GFP_ATOMIC); + size = struct_size(asc_scsi_q->sg_head, sg_list, use_sg); + asc_sg_head = kzalloc(size, GFP_ATOMIC); if (!asc_sg_head) { scsi_dma_unmap(scp); set_host_byte(scp, DID_SOFT_ERROR);
As noted in the "Deprecated Interfaces, Language Features, Attributes, and Conventions" documentation [1], size calculations (especially multiplication) should not be performed in memory allocator (or similar) function arguments due to the risk of them overflowing. This could lead to values wrapping around and a smaller allocation being made than the caller was expecting. Using those allocations could lead to linear overflows of heap memory and other misbehaviors. So, refactor the code a bit to use the struct_size() helper instead of the argument "size + count * size" in the kzalloc() function. [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments Signed-off-by: Len Baker <len.baker@gmx.com> --- drivers/scsi/advansys.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) -- 2.25.1