[PATCH v2 1/4] misc: fastrpc: Add NULL check to fastrpc_buf_free to prevent crash

[Jianping Li]

From: Ekansh Gupta <ekansh.gu...@oss.qualcomm.com>

The fastrpc_buf_free function currently does not handle the case where
the input buffer pointer (buf) is NULL. This can lead to a null pointer
dereference, causing a crash or undefined behavior when the function
attempts to access members of the buf structure. Add a NULL check to
ensure safe handling of NULL pointers and prevent potential crashes.

Fixes: c68cfb718c8f9 ("misc: fastrpc: Add support for context Invoke method")
Cc: sta...@kernel.org
Co-developed-by: Ekansh Gupta <ekansh.gu...@oss.qualcomm.com>
Signed-off-by: Ekansh Gupta <ekansh.gu...@oss.qualcomm.com>
Signed-off-by: Jianping Li <jianping...@oss.qualcomm.com>
---
 drivers/misc/fastrpc.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index 4f5a79c50f58..515a43c9d95d 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -414,6 +414,9 @@ static int fastrpc_map_lookup(struct fastrpc_user *fl, int 
fd,
 
 static void fastrpc_buf_free(struct fastrpc_buf *buf)
 {
+       if (!buf)
+               return;
+
        dma_free_coherent(buf->dev, buf->size, buf->virt,
                          fastrpc_ipa_to_dma_addr(buf->fl->cctx, 
buf->dma_addr));
        kfree(buf);
@@ -510,8 +513,7 @@ static void fastrpc_context_free(struct kref *ref)
        for (i = 0; i < ctx->nbufs; i++)
                fastrpc_map_put(ctx->maps[i]);
 
-       if (ctx->buf)
-               fastrpc_buf_free(ctx->buf);
+       fastrpc_buf_free(ctx->buf);
 
        spin_lock_irqsave(&cctx->lock, flags);
        idr_remove(&cctx->ctx_idr, ctx->ctxid >> 4);
@@ -1591,8 +1593,7 @@ static int fastrpc_device_release(struct inode *inode, 
struct file *file)
        list_del(&fl->user);
        spin_unlock_irqrestore(&cctx->lock, flags);
 
-       if (fl->init_mem)
-               fastrpc_buf_free(fl->init_mem);
+       fastrpc_buf_free(fl->init_mem);
 
        list_for_each_entry_safe(ctx, n, &fl->pending, node) {
                list_del(&ctx->node);
@@ -2492,8 +2493,7 @@ static void fastrpc_rpmsg_remove(struct rpmsg_device 
*rpdev)
        list_for_each_entry_safe(buf, b, &cctx->invoke_interrupted_mmaps, node)
                list_del(&buf->node);
 
-       if (cctx->remote_heap)
-               fastrpc_buf_free(cctx->remote_heap);
+       fastrpc_buf_free(cctx->remote_heap);
 
        of_platform_depopulate(&rpdev->dev);
 
-- 
2.43.0