Messages in this thread | | | Date | Tue, 25 Jul 2023 23:30:17 -0700 | From | Bjorn Andersson <> | Subject | Re: [PATCH v2] misc: fastrpc: Fix incorrect DMA mapping unmap request |
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On Mon, Jul 24, 2023 at 12:39:31PM +0530, Ekansh Gupta wrote: > Scatterlist table is obtained during map create request and the same
I'm guessing that this all happens in fastrpc_map_create() where:
map->table = dma_buf_map_attachment_unlocked(map->attach, DMA_BIDIRECTIONAL);
fails, we jump to map_err, and then call fastrpc_map_put(map), which then ends up in the code below?
> table is used for DMA mapping unmap. In case there is any failure > while getting the sg_table, ERR_PTR is returned instead of sg_table.
The problem isn't that ERR_PTR() is being returned, the problem is that this is being assigned to map->table and you keep running.
> > When the map is getting freed, there is only a non-NULL check of > sg_table which will also be true in case failure was returned instead > of sg_table. This would result in improper unmap request. Add proper > check to avoid bad unmap request. > > Fixes: c68cfb718c8f ("misc: fastrpc: Add support for context Invoke method") > Cc: stable <stable@kernel.org> > Tested-by: Ekansh Gupta <quic_ekangupt@quicinc.com>
You always test your own patches, so no need to declare this.
> Signed-off-by: Ekansh Gupta <quic_ekangupt@quicinc.com> > --- > Changes in v2: > - Added fixes information to commit text > > drivers/misc/fastrpc.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c > index 9666d28..75da69a 100644 > --- a/drivers/misc/fastrpc.c > +++ b/drivers/misc/fastrpc.c > @@ -313,7 +313,7 @@ static void fastrpc_free_map(struct kref *ref) > > map = container_of(ref, struct fastrpc_map, refcount); > > - if (map->table) { > + if (map->table && !IS_ERR(map->table)) {
Rather than carrying around an IS_ERR(map->table), I think you should address this at the originating place. E.g. assign the return value of the dma_buf_map_attachment_unlocked() to a local variable and only if it is valid you assign map->table. Or perhaps make it NULL in the error path.
Regards, Bjorn
> if (map->attr & FASTRPC_ATTR_SECUREMAP) { > struct qcom_scm_vmperm perm; > int vmid = map->fl->cctx->vmperms[0].vmid; > -- > 2.7.4 >
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