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misc: fastrpc: fix memory corruption on open

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commit d245f43aab2b61195d8ebb64cef7b5a08c590ab4 upstream.

The probe session-duplication overflow check incremented the session
count also when there were no more available sessions so that memory
beyond the fixed-size slab-allocated session array could be corrupted in
fastrpc_session_alloc() on open().

Fixes: f6f9279f2b ("misc: fastrpc: Add Qualcomm fastrpc basic driver model")
Cc: stable@vger.kernel.org      # 5.1
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20220829080531.29681-3-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Johan Hovold 2022-08-29 10:05:30 +02:00 committed by Greg Kroah-Hartman
parent ec186b9f4a
commit f8632b8bb5
1 changed files with 3 additions and 4 deletions
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7
drivers/misc/fastrpc.c
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@ -1362,7 +1362,7 @@ static int fastrpc_cb_probe(struct platform_device *pdev)
spin_unlock_irqrestore(&cctx->lock, flags); spin_unlock_irqrestore(&cctx->lock, flags);
return -ENOSPC; return -ENOSPC;
} }
sess = &cctx->session[cctx->sesscount]; sess = &cctx->session[cctx->sesscount++];
sess->used = false; sess->used = false;
sess->valid = true; sess->valid = true;
sess->dev = dev; sess->dev = dev;
@ -1375,13 +1375,12 @@ static int fastrpc_cb_probe(struct platform_device *pdev)
struct fastrpc_session_ctx *dup_sess; struct fastrpc_session_ctx *dup_sess;
for (i = 1; i < sessions; i++) { for (i = 1; i < sessions; i++) {
if (cctx->sesscount++ >= FASTRPC_MAX_SESSIONS) if (cctx->sesscount >= FASTRPC_MAX_SESSIONS)
break; break;
dup_sess = &cctx->session[cctx->sesscount]; dup_sess = &cctx->session[cctx->sesscount++];
memcpy(dup_sess, sess, sizeof(*dup_sess)); memcpy(dup_sess, sess, sizeof(*dup_sess));
} }
} }
cctx->sesscount++;
spin_unlock_irqrestore(&cctx->lock, flags); spin_unlock_irqrestore(&cctx->lock, flags);
rc = dma_set_mask(dev, DMA_BIT_MASK(32)); rc = dma_set_mask(dev, DMA_BIT_MASK(32));
if (rc) { if (rc) {