我试图在Ubuntu虚拟机上运行一个简单的R脚本（使用Oracle Virtual Box）。每当我尝试使用日期格式化函数as.POSIXct时，我都会收到缓冲区溢出错误（见下文）。 知道什么可能导致这个缓冲区溢出？有没有办法可以增加缓冲区的大小以避免它？
感谢您的帮助！
> a<-as.POSIXct('2015-04-21')
*** buffer overflow detected ***: /usr/lib/R/bin/exec/R terminated
======= Backtrace: =========
/lib/x86_64-linux-gnu/libc.so.6(+0x741cf)[0x7f5450de21cf]
/lib/x86_64-linux-gnu/libc.so.6(__fortify_fail+0x5c)[0x7f5450e79b2c]
/lib/x86_64-linux-gnu/libc.so.6(+0x10a9f0)[0x7f5450e789f0]
/lib/x86_64-linux-gnu/libc.so.6(+0x10cd6a)[0x7f5450e7ad6a]
/usr/lib/R/lib/libR.so(+0x926c4)[0x7f54513e46c4]
/usr/lib/R/lib/libR.so(+0x9446b)[0x7f54513e646b]
/usr/lib/R/lib/libR.so(+0xdcddb)[0x7f545142eddb]
/usr/lib/R/lib/libR.so(Rf_eval+0xf8)[0x7f5451436d98]
/usr/lib/R/lib/libR.so(Rf_applyClosure+0x346)[0x7f5451438056]
/usr/lib/R/lib/libR.so(+0xdbfc6)[0x7f545142dfc6]
/usr/lib/R/lib/libR.so(Rf_eval+0xf8)[0x7f5451436d98]
/usr/lib/R/lib/libR.so(Rf_applyClosure+0x346)[0x7f5451438056]
/usr/lib/R/lib/libR.so(+0x11a3bb)[0x7f545146c3bb]
/usr/lib/R/lib/libR.so(+0x11a811)[0x7f545146c811]
/usr/lib/R/lib/libR.so(+0xdcf50)[0x7f545142ef50]
/usr/lib/R/lib/libR.so(Rf_eval+0xf8)[0x7f5451436d98]
/usr/lib/R/lib/libR.so(Rf_applyClosure+0x346)[0x7f5451438056]
/usr/lib/R/lib/libR.so(+0xdbfc6)[0x7f545142dfc6]
/usr/lib/R/lib/libR.so(Rf_eval+0xf8)[0x7f5451436d98]
/usr/lib/R/lib/libR.so(+0xe5530)[0x7f5451437530]
/usr/lib/R/lib/libR.so(Rf_eval+0x598)[0x7f5451437238]
/usr/lib/R/lib/libR.so(+0x11a955)[0x7f545146c955]
/usr/lib/R/lib/libR.so(+0xdcf50)[0x7f545142ef50]
/usr/lib/R/lib/libR.so(Rf_eval+0xf8)[0x7f5451436d98]
/usr/lib/R/lib/libR.so(Rf_applyClosure+0x346)[0x7f5451438056]
/usr/lib/R/lib/libR.so(+0xdbfc6)[0x7f545142dfc6]
/usr/lib/R/lib/libR.so(Rf_eval+0xf8)[0x7f5451436d98]
/usr/lib/R/lib/libR.so(Rf_applyClosure+0x346)[0x7f5451438056]
/usr/lib/R/lib/libR.so(+0x11a3bb)[0x7f545146c3bb]
/usr/lib/R/lib/libR.so(+0x11a811)[0x7f545146c811]
/usr/lib/R/lib/libR.so(+0xdcf50)[0x7f545142ef50]
/usr/lib/R/lib/libR.so(Rf_eval+0xf8)[0x7f5451436d98]
/usr/lib/R/lib/libR.so(Rf_applyClosure+0x346)[0x7f5451438056]
/usr/lib/R/lib/libR.so(Rf_eval+0x26d)[0x7f5451436f0d]
/usr/lib/R/lib/libR.so(+0xe7d18)[0x7f5451439d18]
/usr/lib/R/lib/libR.so(Rf_eval+0x42d)[0x7f54514370cd]
/usr/lib/R/lib/libR.so(Rf_ReplIteration+0x1bd)[0x7f545145fbbd]
/usr/lib/R/lib/libR.so(+0x10ded1)[0x7f545145fed1]
/usr/lib/R/lib/libR.so(run_Rmainloop+0x44)[0x7f545145ff64]
/usr/lib/R/bin/exec/R(main+0x1b)[0x40082b]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf5)[0x7f5450d8fec5]
/usr/lib/R/bin/exec/R[0x40085b]
======= Memory map: ========
00400000-00401000 r-xp 00000000 08:01 301486 /usr/lib/R/bin/exec/R
00600000-00601000 r--p 00000000 08:01 301486 /usr/lib/R/bin/exec/R
00601000-00602000 rw-p 00001000 08:01 301486 /usr/lib/R/bin/exec/R
012f7000-02d5b000 rw-p 00000000 00:00 0 [heap]
7f544c68b000-7f544c6c6000 r-xp 00000000 08:01 274513 /usr/lib/x86_64-linux-gnu/libquadmath.so.0.0.0
7f544c6c6000-7f544c8c5000 ---p 0003b000 08:01 274513 /usr/lib/x86_64-linux-gnu/libquadmath.so.0.0.0
7f544c8c5000-7f544c8c6000 r--p 0003a000 08:01 274513 /usr/lib/x86_64-linux-gnu/libquadmath.so.0.0.0
7f544c8c6000-7f544c8c7000 rw-p 0003b000 08:01 274513 /usr/lib/x86_64-linux-gnu/libquadmath.so.0.0.0
7f544c8c7000-7f544c8dd000 r-xp 00000000 08:01 138163 /lib/x86_64-linux-gnu/libgcc_s.so.1
7f544c8dd000-7f544cadc000 ---p 00016000 08:01 138163 /lib/x86_64-linux-gnu/libgcc_s.so.1
7f544cadc000-7f544cadd000 rw-p 00015000 08:01 138163 /lib/x86_64-linux-gnu/libgcc_s.so.1
7f544cadd000-7f544cbf3000 r-xp 00000000 08:01 264669 /usr/lib/x86_64-linux-gnu/libgfortran.so.3.0.0
7f544cbf3000-7f544cdf3000 ---p 00116000 08:01 264669 /usr/lib/x86_64-linux-gnu/libgfortran.so.3.0.0
7f544cdf3000-7f544cdf4000 r--p 00116000 08:01 264669 /usr/lib/x86_64-linux-gnu/libgfortran.so.3.0.0
7f544cdf4000-7f544cdf6000 rw-p 00117000 08:01 264669 /usr/lib/x86_64-linux-gnu/libgfortran.so.3.0.0
7f544cdf6000-7f544d38e000 r-xp 00000000 08:01 300537 /usr/lib/lapack/liblapack.so.3.0
7f544d38e000-7f544d58d000 ---p 00598000 08:01 300537 /usr/lib/lapack/liblapack.so.3.0
7f544d58d000-7f544d58e000 r--p 00597000 08:01 300537 /usr/lib/lapack/liblapack.so.3.0
7f544d58e000-7f544d592000 rw-p 00598000 08:01 300537 /usr/lib/lapack/liblapack.so.3.0
7f544d592000-7f544d650000 r-xp 00000000 08:01 301108 /usr/lib/R/library/stats/libs/stats.so
7f544d650000-7f544d850000 ---p 000be000 08:01 301108 /usr/lib/R/library/stats/libs/stats.so
7f544d850000-7f544d852000 r--p 000be000 08:01 301108 /usr/lib/R/library/stats/libs/stats.so
7f544d852000-7f544d854000 rw-p 000c0000 08:01 301108 /usr/lib/R/library/stats/libs/stats.so
7f544d854000-7f544d89b000 r-xp 00000000 08:01 301217 /usr/lib/R/library/graphics/libs/graphics.so
7f544d89b000-7f544da9a000 ---p 00047000 08:01 301217 /usr/lib/R/library/graphics/libs/graphics.so
7f544da9a000-7f544da9b000 r--p 00046000 08:01 301217 /usr/lib/R/library/graphics/libs/graphics.so
7f544da9b000-7f544da9c000 rw-p 00047000 08:01 301217 /usr/lib/R/library/graphics/libs/graphics.so
7f544da9c000-7f544dad6000 r-xp 00000000 08:01 301256 /usr/lib/R/library/grDevices/libs/grDevices.so
7f544dad6000-7f544dcd6000 ---p 0003a000 08:01 301256 /usr/lib/R/library/grDevices/libs/grDevices.so
7f544dcd6000-7f544dcdb000 r--p 0003a000 08:01 301256 /usr/lib/R/library/grDevices/libs/grDevices.so
7f544dcdb000-7f544dcdd000 rw-p 0003f000 08:01 301256 /usr/lib/R/library/grDevices/libs/grDevices.so
7f544dcdd000-7f544dcde000 rw-p 00000000 00:00 0
7f544de1b000-7f544de1d000 r-xp 00000000 08:01 400578 /usr/lib/x86_64-linux-gnu/gconv/ISO8859-1.so
7f544de1d000-7f544e01c000 ---p 00002000 08:01 400578 /usr/lib/x86_64-linux-gnu/gconv/ISO8859-1.so
7f544e01c000-7f544e01d000 r--p 00001000 08:01 400578 /usr/lib/x86_64-linux-gnu/gconv/ISO8859-1.so
7f544e01d000-7f544e01e000 rw-p 00002000 08:01 400578 /usr/lib/x86_64-linux-gnu/gconv/ISO8859-1.so
7f544e01e000-7f544e127000 rw-p 00000000 00:00 0
7f544e127000-7f544e12f000 r-xp 00000000 08:01 300959 /usr/lib/R/library/methods/libs/methods.so
7f544e12f000-7f544e32e000 ---p 00008000 08:01 300959 /usr/lib/R/library/methods/libs/methods.so
7f544e32e000-7f544e32f000 r--p 00007000 08:01 300959 /usr/lib/R/library/methods/libs/methods.so
7f544e32f000-7f544e330000 rw-p 00008000 08:01 300959 /usr/lib/R/library/methods/libs/methods.so
7f544e330000-7f544e33c000 r-xp 00000000 08:01 301185 /usr/lib/R/library/utils/libs/utils.so
7f544e33c000-7f544e53b000 ---p 0000c000 08:01 301185 /usr/lib/R/library/utils/libs/utils.so
7f544e53b000-7f544e53c000 r--p 0000b000 08:01 301185 /usr/lib/R/library/utils/libs/utils.so
7f544e53c000-7f544e53d000 rw-p 0000c000 08:01 301185 /usr/lib/R/library/utils/libs/utils.so
7f544e53d000-7f544e53e000 rw-p 00000000 00:00 0
7f544e53e000-7f544e549000 r-xp 00000000 08:01 138211 /lib/x86_64-linux-gnu/libnss_files-2.19.so
7f544e549000-7f544e748000 ---p 0000b000 08:01 138211 /lib/x86_64-linux-gnu/libnss_files-2.19.so
7f544e748000-7f544e749000 r--p 0000a000 08:01 138211 /lib/x86_64-linux-gnu/libnss_files-2.19.so
7f544e749000-7f544e74a000 rw-p 0000b000 08:01 138211 /lib/x86_64-linux-gnu/libnss_files-2.19.so
7f544e74a000-7f544e755000 r-xp 00000000 08:01 138221 /lib/x86_64-linux-gnu/libnss_nis-2.19.so
7f544e755000-7f544e954000 ---p 0000b000 08:01 138221 /lib/x86_64-linux-gnu/libnss_nis-2.19.so
7f544e954000-7f544e955000 r--p 0000a000 08:01 138221 /lib/x86_64-linux-gnu/libnss_nis-2.19.so
7f544e955000-7f544e956000 rw-p 0000b000 08:01 138221 /lib/x86_64-linux-gnu/libnss_nis-2.19.so
7f544e9d1000-7f544e9e8000 r-xp 00000000 08:01 138205 /lib/x86_64-linux-gnu/libnsl-2.19.so
7f544e9e8000-7f544ebe7000 ---p 00017000 08:01 138205 /lib/x86_64-linux-gnu/libnsl-2.19.so
7f544ebe7000-7f544ebe8000 r--p 00016000 08:01 138205 /lib/x86_64-linux-gnu/libnsl-2.19.so
7f544ebe8000-7f544ebe9000 rw-p 00017000 08:01 138205 /lib/x86_64-linux-gnu/libnsl-2.19.so
7f544ebe9000-7f544ebeb000 rw-p 00000000 00:00 0
7f544ebeb000-7f544ebf4000 r-xp 00000000 08:01 138207 /lib/x86_64-linux-gnu/libnss_compat-2.19.so
7f544ebf4000-7f544edf3000 ---p 00009000 08:01 138207 /lib/x86_64-linux-gnu/libnss_compat-2.19.so
7f544edf3000-7f544edf4000 r--p 00008000 08:01 138207 /lib/x86_64-linux-gnu/libnss_compat-2.19.so
7f544edf4000-7f544edf5000 rw-p 00009000 08:01 138207 /lib/x86_64-linux-gnu/libnss_compat-2.19.so
7f544edf5000-7f544f4d8000 r--p 00000000 08:01 271098 /usr/lib/locale/locale-archive
7f544f4d8000-7f544f4fd000 r-xp 00000000 08:01 138282 /lib/x86_64-linux-gnu/libtinfo.so.5.9
7f544f4fd000-7f544f6fc000 ---p 00025000 08:01 138282 /lib/x86_64-linux-gnu/libtinfo.so.5.9
7f544f6fc000-7f544f700000 r--p 00024000 08:01 138282 /lib/x86_64-linux-gnu/libtinfo.so.5.9
7f544f700000-7f544f701000 rw-p 00028000 08:01 138282 /lib/x86_64-linux-gnu/libtinfo.so.5.9
7f544f701000-7f544f70e000 r-xp 00000000 08:01 274120 /usr/lib/x86_64-linux-gnu/libgomp.so.1.0.0
7f544f70e000-7f544f90e000 ---p 0000d000 08:01 274120 /usr/lib/x86_64-linux-gnu/libgomp.so.1.0.0
7f544f90e000-7f544f90f000 r--p 0000d000 08:01 274120 /usr/lib/x86_64-linux-gnu/libgomp.so.1.0.0
7f544f90f000-7f544f910000 rw-p 0000e000 08:01 274120 /usr/lib/x86_64-linux-gnu/libgomp.so.1.0.0
7f544f910000-7f544f913000 r-xp 00000000 08:01 138153 /lib/x86_64-linux-gnu/libdl-2.19.so
7f544f913000-7f544fb12000 ---p 00003000 08:01 138153 /lib/x86_64-linux-gnu/libdl-2.19.so
7f544fb12000-7f544fb13000 r--p 00002000 08:01 138153 /lib/x86_64-linux-gnu/libdl-2.19.so
7f544fb13000-7f544fb14000 rw-p 00003000 08:01 138153 /lib/x86_64-linux-gnu/libdl-2.19.so
7f544fb14000-7f544fb1b000 r-xp 00000000 08:01 138264 /lib/x86_64-linux-gnu/librt-2.19.so
7f544fb1b000-7f544fd1a000 ---p 00007000 08:01 138264 /lib/x86_64-linux-gnu/librt-2.19.so
7f544fd1a000-7f544fd1b000 r--p 00006000 08:01 138264 /lib/x86_64-linux-gnu/librt-2.19.so
7f544fd1b000-7f544fd1c000 rw-p 00007000 08:01 138264 /lib/x86_64-linux-gnu/librt-2.19.so
7f544fd1c000-7f544fd34000 r-xp 00000000 08:01 138299 /lib/x86_64-linux-gnu/libz.so.1.2.8
7f544fd34000-7f544ff33000 ---p 00018000 08:01 138299 /lib/x86_64-linux-gnu/libz.so.1.2.8
7f544ff33000-7f544ff34000 r--p 00017000 08:01 138299 /lib/x86_64-linux-gnu/libz.so.1.2.8
7f544ff34000-7f544ff35000 rw-p 00018000 08:01 138299 /lib/x86_64-linux-gnu/libz.so.1.2.8
7f544ff35000-7f544ff44000 r-xp 00000000 08:01 138135 /lib/x86_64-linux-gnu/libbz2.so.1.0.4
7f544ff44000-7f5450143000 ---p 0000f000 08:01 138135 /lib/x86_64-linux-gnu/libbz2.so.1.0.4
7f5450143000-7f5450144000 r--p 0000e000 08:01 138135 /lib/x86_64-linux-gnu/libbz2.so.1.0.4
7f5450144000-7f5450145000 rw-p 0000f000 08:01 138135 /lib/x86_64-linux-gnu/libbz2.so.1.0.4
7f5450145000-7f5450166000 r-xp 00000000 08:01 138183 /lib/x86_64-linux-gnu/liblzma.so.5.0.0
7f5450166000-7f5450365000 ---p 00021000 08:01 138183 /lib/x86_64-linux-gnu/liblzma.so.5.0.0
7f5450365000-7f5450366000 r--p 00020000 08:01 138183 /lib/x86_64-linux-gnu/liblzma.so.5.0.0
7f5450366000-7f5450367000 rw-p 00021000 08:01 138183 /lib/x86_64-linux-gnu/liblzma.so.5.0.0
7f5450367000-7f54503a4000 r-xp 00000000 08:01 138239 /lib/x86_64-linux-gnu/libpcre.so.3.13.1
7f54503a4000-7f54505a3000 ---p 0003d000 08:01 138239 /lib/x86_64-linux-gnu/libpcre.so.3.13.1
7f54505a3000-7f54505a4000 r--p 0003c000 08:01 138239 /lib/x86_64-linux-gnu/libpcre.so.3.13.1
7f54505a4000-7f54505a5000 rw-p 0003d000 08:01 138239 /lib/x86_64-linux-gnu/libpcre.so.3.13.1
7f54505a5000-7f54505e2000 r-xp 00000000 08:01 138261 /lib/x86_64-linux-gnu/libreadline.so.6.3
7f54505e2000-7f54507e2000 ---p 0003d000 08:01 138261 /lib/x86_64-linux-gnu/libreadline.so.6.3
7f54507e2000-7f54507e4000 r--p 0003d000 08:01 138261 /lib/x86_64-linux-gnu/libreadline.so.6.3
7f54507e4000-7f54507ea000 rw-p 0003f000 08:01 138261 /lib/x86_64-linux-gnu/libreadline.so.6.3
7f54507ea000-7f54507eb000 rw-p 00000000 00:00 0
7f54507eb000-7f54508f0000 r-xp 00000000 08:01 138186 /lib/x86_64-linux-gnu/libm-2.19.so
7f54508f0000-7f5450aef000 ---p 00105000 08:01 138186 /lib/x86_64-linux-gnu/libm-2.19.so
7f5450aef000-7f5450af0000 r--p 00104000 08:01 138186 /lib/x86_64-linux-gnu/libm-2.19.so
7f5450af0000-7f5450af1000 rw-p 00105000 08:01 138186 /lib/x86_64-linux-gnu/libm-2.19.so
7f5450af1000-7f5450b6d000 r-xp 00000000 08:01 300518 /usr/lib/libblas/libblas.so.3.0
7f5450b6d000-7f5450d6c000 ---p 0007c000 08:01 300518 /usr/lib/libblas/libblas.so.3.0
7f5450d6c000-7f5450d6d000 r--p 0007b000 08:01 300518 /usr/lib/libblas/libblas.so.3.0
7f5450d6d000-7f5450d6e000 rw-p 0007c000 08:01 300518 /usr/lib/libblas/libblas.so.3.0
7f5450d6e000-7f5450f2a000 r-xp 00000000 08:01 138136 /lib/x86_64-linux-gnu/libc-2.19.so
7f5450f2a000-7f5451129000 ---p 001bc000 08:01 138136 /lib/x86_64-linux-gnu/libc-2.19.so
7f5451129000-7f545112d000 r--p 001bb000 08:01 138136 /lib/x86_64-linux-gnu/libc-2.19.so
7f545112d000-7f545112f000 rw-p 001bf000 08:01 138136 /lib/x86_64-linux-gnu/libc-2.19.so
7f545112f000-7f5451134000 rw-p 00000000 00:00 0
7f5451134000-7f545114d000 r-xp 00000000 08:01 138256 /lib/x86_64-linux-gnu/libpthread-2.19.so
7f545114d000-7f545134c000 ---p 00019000 08:01 138256 /lib/x86_64-linux-gnu/libpthread-2.19.so
7f545134c000-7f545134d000 r--p 00018000 08:01 138256 /lib/x86_64-linux-gnu/libpthread-2.19.so
7f545134d000-7f545134e000 rw-p 00019000 08:01 138256 /lib/x86_64-linux-gnu/libpthread-2.19.so
7f545134e000-7f5451352000 rw-p 00000000 00:00 0
7f5451352000-7f54515a7000 r-xp 00000000 08:01 301472 /usr/lib/R/lib/libR.so
7f54515a7000-7f54517a7000 ---p 00255000 08:01 301472 /usr/lib/R/lib/libR.so
7f54517a7000-7f54517ac000 r--p 00255000 08:01 301472 /usr/lib/R/lib/libR.so
7f54517ac000-7f54517b6000 rw-p 0025a000 08:01 301472 /usr/lib/R/lib/libR.so
7f54517b6000-7f54518a2000 rw-p 00000000 00:00 0
7f54518a2000-7f54518c5000 r-xp 00000000 08:01 138112 /lib/x86_64-linux-gnu/ld-2.19.so
7f54518fd000-7f5451aae000 rw-p 00000000 00:00 0
7f5451ab8000-7f5451ab9000 rw-p 00000000 00:00 0
7f5451ab9000-7f5451aba000 r--p 00000000 08:01 300955 /usr/lib/R/library/translations/en/LC_MESSAGES/R.mo
7f5451aba000-7f5451ac1000 r--s 00000000 08:01 400634 /usr/lib/x86_64-linux-gnu/gconv/gconv-modules.cache
7f5451ac1000-7f5451ac4000 rw-p 00000000 00:00 0
7f5451ac4000-7f5451ac5000 r--p 00022000 08:01 138112 /lib/x86_64-linux-gnu/ld-2.19.so
7f5451ac5000-7f5451ac6000 rw-p 00023000 08:01 138112 /lib/x86_64-linux-gnu/ld-2.19.so
7f5451ac6000-7f5451ac7000 rw-p 00000000 00:00 0
7fffd4001000-7fffd402c000 rw-p 00000000 00:00 0 [stack]
7fffd41bd000-7fffd41bf000 r-xp 00000000 00:00 0 [vdso]
ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 [vsyscall]