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<a href="https://gitlab.rtems.org/D3athSkulll">SHIVAM DEOLANKAR</a>
<a href="https://gitlab.rtems.org/rtems/rtos/rtems/-/issues/5558#note_149038">commented</a>:
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<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">I have reviewed the shared bsp folders for the following analysis. ns16550 files need a change for this similar to the attached MR.</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial"><strong style="font-weight: 600; margin-top: 0;">Reviewed <code style="font-size: 90%; color: #18171d; word-wrap: break-word; background-color: #ececef; border-radius: .25rem; margin-top: 0; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; white-space: pre-wrap; overflow-wrap: break-word; word-break: keep-all; padding: 0.125rem 0.25rem;">z85c30_set_attributes()</code> in z85c30.c</strong><br>
The driver already guards against zero baud rate using assertions and runtime checks. No division-by-zero risk exists. Behavior differs slightly (defaults to 9600 for B0), but it is safe.</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">Reviewed <code style="font-size: 90%; color: #18171d; word-wrap: break-word; background-color: #ececef; border-radius: .25rem; margin-top: 0; font-weight: inherit; overflow-wrap: break-word; white-space: break-spaces; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: keep-all; padding: 0.125rem 0.25rem;">versal_uart_set_attributes()</code> in <strong style="font-weight: 600;">versal-uart.c</strong></p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">The driver safely handles <code style="font-size: 90%; color: #18171d; word-wrap: break-word; background-color: #ececef; border-radius: .25rem; margin-top: 0; font-weight: inherit; overflow-wrap: break-word; white-space: break-spaces; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: keep-all; padding: 0.125rem 0.25rem;">baud == 0</code> by skipping baud configuration. No division or unsafe computation occurs. B0 is explicitly ignored, consistent with lack of modem control support. No changes required.</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">Reviewed <code style="font-size: 90%; color: #18171d; word-wrap: break-word; background-color: #ececef; border-radius: .25rem; margin-top: 0; font-weight: inherit; overflow-wrap: break-word; white-space: break-spaces; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: keep-all; padding: 0.125rem 0.25rem;">zynq_uart_set_attributes()</code> in <strong style="font-weight: 600;">zynq-uart.c.</strong></p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">The driver safely handles baud rate 0 by guarding all computations and hardware updates with <code style="font-size: 90%; color: #18171d; word-wrap: break-word; background-color: #ececef; border-radius: .25rem; margin-top: 0; font-weight: inherit; overflow-wrap: break-word; white-space: break-spaces; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: keep-all; padding: 0.125rem 0.25rem;">desired_baud > 0</code>. B0 is explicitly ignored, and no division-by-zero risk exists. No changes required.</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">Reviewed <code style="font-size: 90%; color: #18171d; word-wrap: break-word; background-color: #ececef; border-radius: .25rem; margin-top: 0; font-weight: inherit; overflow-wrap: break-word; white-space: break-spaces; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: keep-all; padding: 0.125rem 0.25rem;">ns16550_set_attributes()</code> in <strong style="font-weight: 600;"><em style="margin-top: 0;">ns16550-context.c.</em></strong></p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">The function relies on <code style="font-size: 90%; color: #18171d; word-wrap: break-word; background-color: #ececef; border-radius: .25rem; margin-top: 0; font-weight: inherit; overflow-wrap: break-word; white-space: break-spaces; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: keep-all; padding: 0.125rem 0.25rem;">_Assert(baud_requested != 0)</code> but lacks a runtime guard. Since assertions may be disabled, this can lead to divide-by-zero in <code style="font-size: 90%; color: #18171d; word-wrap: break-word; background-color: #ececef; border-radius: .25rem; font-weight: inherit; overflow-wrap: break-word; white-space: break-spaces; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: keep-all; padding: 0.125rem 0.25rem;">NS16550_GetBaudDivisor()</code>. Need to add explicit check to return false when baud is 0 similar to MR <a href="https://gitlab.rtems.org/rtems/rtos/rtems/-/merge_requests/1216" title="bsp/arm/tms570: protect against baud rate divide-by-zero" class="gfm gfm-merge_request" data-original="!1216" data-link="false" data-link-reference="false" data-merge-request="2540" data-project="26" data-project-path="rtems/rtos/rtems" data-iid="1216" data-container="body" data-placement="top" data-reference-type="merge_request">!1216 (merged)</a>.</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">Reviewed <code style="font-size: 90%; color: #18171d; word-wrap: break-word; background-color: #ececef; border-radius: .25rem; margin-top: 0; font-weight: inherit; overflow-wrap: break-word; white-space: break-spaces; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: keep-all; padding: 0.125rem 0.25rem;">ns16550_set_attributes()</code> in <strong style="font-weight: 600;"><em style="margin-top: 0;">ns16550.c.</em></strong></p>
<p dir="auto" style="color: #3a383f; margin: 0;" align="initial">The function relies solely on <code style="font-size: 90%; color: #18171d; word-wrap: break-word; background-color: #ececef; border-radius: .25rem; margin-top: 0; font-weight: inherit; overflow-wrap: break-word; white-space: break-spaces; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: keep-all; padding: 0.125rem 0.25rem;">_Assert</code> to prevent zero baud rate. Since assertions may be disabled, this can lead to divide-by-zero in <code style="font-size: 90%; color: #18171d; word-wrap: break-word; background-color: #ececef; border-radius: .25rem; font-weight: inherit; overflow-wrap: break-word; white-space: break-spaces; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: keep-all; padding: 0.125rem 0.25rem;">NS16550_GetBaudDivisor()</code>. We can add runtime check to return error when baud is 0.</p>
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