Hi Naveen, On 7/8/26 4:33 PM, Naveen Kumar Chaudhary wrote:
The '/' and '%' arms of the operator switch in do_setexpr() perform a / b and a % b directly on the user-supplied ulongs with no check that b is non-zero. The consequences are architecture-dependent:- On x86 and sandbox, integer divide-by-zero raises an exception (#DE / SIGFPE) which aborts the shell. - On arm64, arm, and RISC-V, the UDIV/SDIV instructions are defined to return 0 on a zero divisor and do not trap, so 'setexpr x 10 / 0' silently succeeds and stores 0 into the environment variable, which is a plausible-looking but garbage result. Neither behaviour is acceptable for a scripting primitive. Check b before dividing and print a clear error, returning failure so scripts can detect it. ++++++ Before Fix ++++++++ => setexpr x 0xa / 0 => printenv x x=0 ++++++ After Fix +++++++++ => setexpr x 0xa / 0 Error: division by zero => setexpr x 0xa % 0 Error: modulo by zero => Signed-off-by: Naveen Kumar Chaudhary <[email protected]>
Makes sense to me, though we definitely need new tests for those, c.f. test/cmd/setexpr.c, so we don't regress in the future. Cheers, Quentin
