jerpelea opened a new pull request, #19610:
URL: https://github.com/apache/nuttx/pull/19610

   ## Summary
   
   uart_putxmitchar() manipulates dev->xmit.head/buffer directly with no 
internal locking - every other caller (uart_write()) takes dev->xmit.lock 
first. uart_readv()'s ECHO handling (both the backspace/delete erase sequence 
and the normal character echo) calls uart_putxmitchar() without taking that 
lock, so a concurrent uart_write() and a local echo can race on the same 
circular buffer state, corrupting it.
   
   Take dev->xmit.lock around each echo's uart_putxmitchar() calls, matching 
what uart_write() already does. uart_readv() holds dev->recv.lock for its own 
duration, but no other code path ever acquires recv.lock while holding 
xmit.lock, so nesting xmit.lock inside the existing recv.lock scope here 
doesn't introduce a new lock-ordering cycle.
   
   Fixes #14845
   
   ## Impact
   
   RELEASE
   
   ## Testing
   
   CI


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